- 1947 to 19497,391
- 1950 to 195410,162
- 1955 to 19597,523
- 1960 to 196413,403
- 1965 to 196915,438
- 1970 to 19749,551
- 1975 to 19766,334
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