That's a remarkably low rate, considering that it includes all levels of law enforcement. For instance, around 2000 children are reported missing in the US every day. I would expect a lot of those to lead to local police to ask to see the child's Facebook data, and that alone could account for most of the requests.

Now throw in all the other ordinary crime local police deal with every day, and I'm completely astonished that Facebook only deals with 50 requests a day.