- 1863 to 1869 2,929
- 1870 to 1879 2,658
- 1880 to 1889 3,338
- 1890 to 1899 3,193
- 1900 to 1909 3,436
- 1910 to 1919 8,211
- 1920 to 1929 8,998
- 1930 to 1939 8,300
- 1940 to 1949 12,821
- 1950 to 1959 10,024
- 1960 to 1969 13,544
- 1970 to 1979 7,689
- 1980 to 1989 9,999
- 1990 to 1999 6,493
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