- 1923 to 19296,544
- 1930 to 193910,202
- 1940 to 194915,864
- 1950 to 195914,956
- 1960 to 196922,531
- 1970 to 197914,131
- 1980 to 198914,360
- 1990 to 199910,530
- 20001,098
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