According to the chart, the current homicide rate is about 7/100,000. I found a spreadsheet showing homicides going back to 1849. The rate between 1968 (happy birthday to me) and 1996 is significantly higher than now, bouncing around between 10 and 20. Between 1920 and 1967, it bounces around between a low of 2 (1938) and 9. The 1870s were another relatively high period.

Interestingly, San Francisco's population declined from 775,000 in 1950 to 679,000 in 1980.

Sources:

Homicide in San Francisco, 1849-2003 (https://cjrc.osu.edu/research/interdisciplinary/hvd/united-s...)

Historical population of San Francisco (https://en.wikipedia.org/wiki/Demographics_of_San_Francisco) plus some linear interpolation