- 1850 to 18591,972
- 1860 to 18796,223
- 1880 to 18996,104
- 1900 to 191911,238
- 1920 to 193917,795
- 1940 to 195927,636
- 1960 to 197934,124
- 1980 to 199921,989
- 2000 to 20092,250
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