This sex researcher phones one…

This sex researcher phones one of the participants in a recent survey of his to check on a discrepancy.
He asks the bloke, “In response to the question on frequency of intercourse you answered ‘twice weekly’. Your wife, on the other hand, answered ‘several times a night’.”
“That’s right,” replies the bloke, “And that’s how it’s going to stay until our second mortgage is paid off.”