Abstract

The world produces between 1 and 2 exabytes of unique information per year, which is roughly 250 megabytes for every man, woman, and child on earth. An exabyte is a billion gigabytes, or 10¹⁸ bytes. Printed documents of all kinds comprise only .003% of the total. Magnetic storage is by far the largest medium for storing information and is the most rapidly growing, with shipped hard drive capacity doubling every year. Magnetic storage is rapidly becoming the universal medium for information storage.

Information produced by medium

Most information is stored in four physical media: paper, film, optical (CDs and DVDs), and magnetic. There are very good data for the worldwide production of each storage medium, and there are reasonably good estimates of how much original content is produced in each of these different formats.

We have identified production of content by media type, translated the volume of original content into a common standard (terabytes), determined how much storage each type takes under certain assumptions about compression, attempted to adjust for duplication of content, and added up to get total estimates.

Table 1 depicts yearly worldwide production of original stored content as of 1999. In general, the upper estimate is based on the raw data, while the lower estimate reflects an attempt to adjust for duplication and compression. We discuss these adjustments below and in the medium-specific documents. Note that the growth rate estimates are very rough. See the "Qualifications" section and Appendix A for further discussion; the details of the calculations are presented in the accompanying documents.

Table 1: Worldwide production of original content, stored digitally using standard compression methods, in terabytes circa 1999.
Storage Medium	Type of Content	Terabytes/Year, Upper Estimate	Terabytes/Year, Lower Estimate	Growth Rate, %
Paper	Books	8	1	2
	Newspapers	25	2	-2
	Periodicals	12	1	2
	Office documents	195	19	2
	Subtotal:	240	23	2
Film	Photographs	410,000	41,000	5
	Cinema	16	16	3
	X-Rays	17,200	17,200	2
	Subtotal:	427,216	58,216	4
Optical	Music CDs	58	6	3
	Data CDs	3	3	2
	DVDs	22	22	100
	Subtotal:	83	31	70
Magnetic	Camcorder Tape	300,000	300,000	5
	PC Disk Drives	766,000	7,660	100
	Departmental Servers	460,000	161,000	100
	Enterprise Servers	167,000	108,550	100
	Subtotal:	1,693,000	577,210	55
TOTAL:		2,120,539	635,480	50

Three striking facts emerge from these estimates. The first is the "paucity of print." Printed material of all kinds makes up less than .003 percent of the total storage of information. This doesn't imply that print is insignificant. Quite the contrary: it simply means that the written word is an extremely efficient way to convey information.

The second striking fact is the ``democratization of data.'' A vast amount of unique information is created and stored by individuals. Original documents created by office workers are more than 80% of all original paper documents, while photographs and X-rays together are 99% of all original film documents. Camcorder tapes are also a significant fraction of total magnetic tape storage of unique content, with digital tapes being used primarily for backup copies of material on magnetic drives.

As for hard drives, roughly 55% of the total are installed in single-user desktop computers. Of course, much of the content on individual users' hard drives is not unique, which accounts for the large difference between the upper and lower bounds for magnetic storage. However, as more and more image data moves onto hard drives, we expect to see the amount of digital content produced by individuals stored on hard drives increase dramatically.

This democratization of data is quite remarkable. A century ago the average person could only create and access a small amount of information. Now, ordinary people not only have access to huge amounts of data, but are also able to create gigabytes of data themselves and, potentially, publish it to the world via the Internet, if they choose to do so.

The third interesting finding is the "dominance of digital" content. Not only is digital information production the largest in total, it is also the most rapidly growing. While unique content on print and film are hardly growing at all, optical and digital magnetic storage shipments are doubling each year. Even today, most textual information is "born digital,'' and within a few years this will be true for images as well. Digital information is inexpensive to copy and distribute, is searchable, and is malleable. Thus the trend towards democratization of data---especially in digital form---is likely to continue.

Table 2: Summary of yearly unique computer-mediated information flows.
Content	Terabytes
Email	11,285
Usenet	73

Table 3: Summary of yearly non-digital communication flows in the United States 1999.
Content	Terabytes
Radio	788
TV	14,150
Telephone	576,000
Postal	150,000

Table 4: Summary of yearly media use by US households in hours per year, with estimated megabyte equivalent. (Hours from Statistical Abstract of the United States, 1999, Table 920, (projected)).
Item	1992 Hours	2000 Hours	2000 MBytes	% Change
TV	1510	1571	3,142,000	4
Radio	1150	1056	57,800	-8
Recorded Music	233	269	13,450	15
Newspaper	172	154	11	-10
Books	100	96	7	-4
Magazines	85	80	6	-6
Home video	42	55	110,000	30
Video games	19	43	21,500	126
Internet	2	43	9	2,050
Total:	3,324	3,380	3,344,783	1.7

Table 5: Yearly production of individual information
Item	Amount	Terabytes
Photographs	80 billion images	410,000
Home videos	1.4 billion tapes	300,000
X-rays	2 billion images	17,200
Hard disks	200 million installed drives	13,760
Total:		740,960

Table 6: Yearly production of published information
Item	Titles	Terabytes
Books	968,735	8
Newspapers	22,643	25
Journals	40,000	2
Magazines	80,000	10
Newsletters	40,000	.2
Office Documents	7,500,000,000	195
Cinema	4,000	16
Music CDs	90,000	6
Data CDs	1,000	3
DVD-video	5,000	22
Total:		285

Conclusion

The world's total production of information amounts to about 250 megabytes for each man, woman, and child on earth. It is clear that we are all drowning in a sea of information. The challenge is to learn to swim in that sea, rather than drown in it. Better understanding and better tools are desperately needed if we are to take full advantage of the ever-increasing supply of information described in this report.

About this Report

Financial support for this study was provided by EMC. We view this report as a "living document" and intend to revise it based on comments, corrections, and suggestions. Please send such materials to how-much-info@sims.berkeley.edu.

About the School of Information Management and Systems

UC Berkeley's School of Information Management and Systems is the first school in the nation to explicitly address the growing need to manage information more effectively.

With respect to education, we are training a new type of professional: "information managers". Our graduates are familiar with the latest and most powerful techniques for locating, organizing, retrieving, manipulating, protecting, and presenting information. They study not only technology, but also the institutional, legal, economic and organizational factors necessary for creating information systems that meet peoples' needs.

With respect to research, we are examining ways to build more effective tools and systems for managing information. This effort is inherently multidisciplinary, involving computer science, information science, social science, cognitive science, and legal studies.

Appendices

© 2000 Regents of the University of California