that's not proof they need to reach a monthly quota. It could be a number of things, perhaps the top cop each month get a bonus, or perhaps he wanted to impress his bosses and get a salary promotion or extra vacation days.
I mean, let's say if they solve 100 crimes they get an increased salary. Sure, that's a kind of quota, but that doesn't mean they have to solve 100 crimes to keep their job.
I do agree that its disgusting though. Here in Sweden, cops rather hand out tickets than solving real crime, as each ticket handed out counts as a solved crime. As such, its easy to boost statistics by handing out tickets. They don't have a quota system (and I know that for a fact, I friends with plenty of cops). Sadly, this also means most cops are incapable of handling other crimes. Hell, there's a famous murder from a few years back, where a separate party drew up a list of 10 people in the neighboring area fitting certain criteria that could be the perpetrator. The cops completely ignored this list and took several months solving the murder, as opposed to just taking those 10 people in for questioning. Well, to their surprise, in the end it showed that the murderer were on this top-10 suspect list said party had put together. And they had put it together within 24 hours of the murder.
They also don't bother solving frauds or faked identities, as that requires more resources than handing out tickets do, and as such "isn't worth it" according to the higher-ups. The company I work for have handed out pretty much all of the information they need to catch the perpetrator (including name, address and facebook page), and yet, they don't bother with it.