This led me to look for other questions on the subject--specifically, for questions about police in the country as a whole rather than your own community. The good news is that there are some, and that they go back to 1981. The bad news is that they stop at 2000. The two questions that were asked multiple times: [agree or disagree that] "these days police in most cities treat blacks as fairly as the treat whites" and "do you think the police in most big cities are generally tougher on whites than on blacks, or tougher on blacks than on whites, or do the police treat them both the same?" I summarize the results as percent favorable (agree or treat both the same) minus unfavorable. (The percent saying they were tougher on whites ranged from 0 to 2--I combined them with treat both the same).
Between 1981 and 2000, there was a substantial move towards seeing treatment as less fair. The figures are for blacks and whites combined, but given that blacks are only about 12 percent of the population, there must have been a substantial move in this direction among whites.