A few flaws in the survery come immediately to mind:
1) they only surveyed 34 professionals (that's not a whole lot considering there are 6 billion people here)
2) they only surveyed professionals, not actual run of the mill people (many professionals form an opinion based on long standing beliefs, not actual data)
3) they don't state how many men vs women they surveyed. (a lot of women complain that it doesn't last long enough)
4) by excluding foreplay, they distort the actual number (we all know women love lots of foreplay).