How many rats ?

I was watching CSI:NYC and there was an interesting fact (?) stated in the program that for every 1 person in New York there 6 rats, the next time I was listening to the local radio and complaining that the rats in Nice where causing problems, here they stated that the ratio of Human to Rats were 1:1

So as usual the Americans have to have done it big and better.

New York 6 - Nice France 1

How rats per residence are living where you are ?