References: Pelvic floor prolapse

"More than 50% of women age 50 and older suffer from one or more problems caused by pelvic floor prolapse"

"The cost of surgical management $10 billion dollars per annum."

Maher 2007 suggested 50% of parous women and $1 billion dollars was suggested in 1997.

The above figures sound very high, please could you let us know the references to back this up?

Thanks