- 1952 to 19546,861
- 1955 to 19597,553
- 1960 to 196413,430
- 1965 to 196915,459
- 1970 to 19749,572
- 1975 to 19799,280
- 1980 to 19846,605
- 1985 to 19898,449
- 1990 to 19943,704
- 19951,463
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