Uhh like how many murder cases got solved, how many drunk drivers had their driving licenses revoked, how many speeding tickets went through, how many stolen cars and goods found its original owner, how many pickpocket thieves, shoplifters, bulglar cases got investigated, you know ... Stuff police exist for?

Those stats are typically at the department level. They don't necessarily match the court records either (eg the police may mark a murder case as solved even if the prosecutor thinks the case is too weak and never goes to court).