- 1947 to 19498,307
- 1950 to 195411,020
- 1955 to 19598,413
- 1960 to 196414,146
- 1965 to 196916,157
- 1970 to 197410,131
- 1975 to 19766,781
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