Are there any official or otherwise reliable statistics on how many exotic snakes are currently in the US pet trade?

A friend of mine is arguing that:

The argument that human deaths by constrictor or venomous snakes are really rare does not imply that snakes are inherently safer. Rather, it is because there are very few snakes of this nature kept in the U.S. Dogs kill about 15 Americans each year, but there are 70 million dogs in the U.S., compared to maybe 7,000 or at most 70,000 constrictor or venomous snakes. If snakes kill only one American per year, that means that the rate of deaths for snakes is many orders of magnitude higher than the rate of deaths for dogs.

Dogs - 1 death for every 5,000,000 animals
Snakes - 1 death for every 70,000 animals (71 times higher)
I really think he just pulled the snake number out of thin air. I don't want to counter him with another number I make up.