Questions 5 to 8 are based on the following passage.
One of the main complaints of the city residents in the United States is the number of homeless cats and dogs. It has been estimated by Friends of Animals Incorporation that more than 30 million cats and dogs are wandering through the streets Of the cities. Each year, about a fifth of these animals are destroyed. A survey of 41 cities reports that as much as 15 million dollars is spent in capturing and kilting those animals every year. However, Chicago spends $ 1 000 000 a year in controlling its animal population. On the other hand, though you can find quite a lot of cats and dogs wandering in New York, the city government doesn’ t spend any money on animal control.

What is the source of the statistics given in the passage（）。