According to the 2009/2010 National Pet Owners Survey, 62% of U.S. households own a pet, which equates to 71.4 millions homes.
Total Number of Pets Owned in the U.S. (millions)
Freshwater Fish 171.7
Saltwater Fish 11.2
Small Animal 15.9
* Ownership statistics are gathered from APPA’s 2009/2010 National Pet Owners Survey
Now, let's see how many types I have owned throughout my life:
2 stray cats
cockatiels (younger brother had 2 for 12-14 years)
iguana (15 years old)
various small lizards, frogs, toad
Friends had squirrel monkey, skunk, rabbits, and then your more common pets.