Found it!

https://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/when-women-kill-their-partners

It was a 71.4% drop btw

Figure 9.3 shows that the number of males killed by intimate partners dropped by 71.4% between 1976 and 2002. Researchers and advocates for battered women attribute this dramatic decline to the widespread availability of support services for women, including shelters, crisis counseling, hotlines, and legal measures such as protection and restraining orders. These services offer abused women options for escaping violence and abuse other than taking their partners' lives. Other factors that may have contributed to the decline are the increased ease of obtaining divorce and the generally improved economic conditions for women.