Spam Statistics

Are there any statistics on the success rate of spam? Meaning, out of every 100 million spam messages sent, x result in a sale?

Just curious.

Bloody Vikings!

Spam was introduced in 1937 and within 70 years, Hormel had sold seven billion cans of it. You might consider it a 100 percent success rate.
Whut?

Check out this graphic from a New Scientist story about spam.

0.000008% success rate.

Thanks! Great information.