All data from US Statistical Abstract -
As of 2001, 36.1% of US households include a dog, 31.6% a cat.
20.8% of one person households have a dog, 23.5% a cat.
34.3% of two person households have a dog, 31.3% a cat.
46.2% of three person households have a dog, 37.4% a cat.
50.6% of four person households have a dog, 38.2% a cat.
53.0% of five or more person households have a dog, 39.7% a cat.
