- 1913 to 19142,926
- 1915 to 19197,776
- 1920 to 19246,949
- 1925 to 19295,488
- 1930 to 19344,820
- 1935 to 19396,910
- 1940 to 19446,714
- 1945 to 194911,265
- 1950 to 195410,827
- 1955 to 19598,226
- 19608,311
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