- 1905 to 19093,415
- 1910 to 19199,548
- 1920 to 192910,372
- 1930 to 193911,110
- 1940 to 194916,440
- 1950 to 195915,225
- 1960 to 196922,892
- 1970 to 197914,473
- 1980 to 198914,499
- 1990 to 199910,828
- 20001,241
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