According to the Washington Post database, here is the trend in police shootings of unarmed men over the past six years:
Anything above zero is too high, but it does look like we’ve made some progress since Ferguson. I can only guess at the underlying reason, but I imagine that pressure from Black Lives Matter has a lot to do with it. Protest and publicity sometimes work pretty well when you have a righteous cause.
POSTSCRIPT: The Post database includes only shootings, but shootings account for virtually all incidents of lethal force by police officers. Obviously George Floyd is a very high-profile exception