- 1930 to 193910,209
- 1940 to 194915,870
- 1950 to 195914,963
- 1960 to 196922,622
- 1970 to 197914,272
- 1980 to 198914,379
- 1990 to 199910,609
- 2000 to 20092,847
- 2010 to 20131,240
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