- 1908 to 19092,496
- 1910 to 19112,578
- 1912 to 19143,042
- 1915 to 19162,657
- 1917 to 19196,818
- 1920 to 19213,361
- 1922 to 19245,119
- 1925 to 19263,519
- 1927 to 19293,690
- 1930 to 19312,489
- 19321,427
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