A while back I dug up some rape stats for Sacramento County in the EAR era. They give a good impression as to the context in which the EAR crimes were committed.
[ BTW, 1980, after the end of the EAR crimes, was the all time peak year for rapes in Sacramento Cal (60.75 per 100,000 or 476 reported rapes)]

Here they are (figures rounded up):

In the 1980 census, Sacramento County had a population of 783,381.

Rapes per 100,000 population, Sacramento County:
1976: 46
1977: 55
1978: 55

Total number of rapes (fiqured out from above numbers):
1976: 357
1977: 430
1978: 428

Number of EAR rapes in Sacramento County:
1976: 9
1977: 16
1978: 3

Percentage of Rapes as EAR crimes:
1976: 0.02 percent
1977: 0.04 percent
1978: 0.007 percent

Odds of a Sac Cty female resident being raped by the EAR:
1976: 43,522 to 1
1977: 24,481 to 1
1978: 130,563 to 1

Odds of a Sac Cty female resident being raped by someone not the EAR (per what crimes were considered EAR):
1976: 1,125 to 1
1977: 946 to 1
1978: 921 to 1