Position players pitching over time

This is something I posted on the SABR-List.

David Smith provided a Retrosheet link that has known occurrences of this happening. See Non-Pitchers on the Mound.

I sorted that table by date and then compiled the number of cases by time period. Here is what I got:

1898-99)  13
1900-09)  81
1910-19)  80
1920-29)  62
1930-39)  39
1940-49)  51
1950-59)  36
1960-69)  24
1970-79)  17
1980-89)  58
1990-99)  48
2000-09)  52
2010-19)  304
2020-25)  588