- 1916 to 19197,234
- 1920 to 19246,668
- 1925 to 19295,166
- 1930 to 19344,395
- 1935 to 19396,413
- 1940 to 19445,957
- 1945 to 194910,453
- 1950 to 195410,185
- 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 19864,892
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