- 1850 to 18592,023
- 1860 to 18796,355
- 1880 to 18996,235
- 1900 to 191911,585
- 1920 to 193919,331
- 1940 to 195929,596
- 1960 to 197934,799
- 1980 to 199924,455
- 2000 to 20092,269
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