- 1972 to 19747,217
- 1975 to 19799,260
- 1980 to 19846,590
- 1985 to 19898,426
- 1990 to 19943,684
- 1995 to 19995,109
- 2000 to 20042,093
The preservation of the Duke University Libraries Digital Collections and the Duke Digital Repository programs are supported in part by the Lowell and Eileen Aptman Digital Preservation Fund