Very interesting data from The Economist on prostitution prices

Clicking on the screen shot will enlarge the picture.  The Economist information is available here.  Prices tell us what types of characteristics in women that men like most.  The second slide probably tells us what women don't like to do and the prices make a lot of sense.  Oral sex without a condom is much more dangerous and less desirable than with a condom (similar for splitting out semen or swallowing it).  Having sex with multiple men is more work.  What seems most interesting here is that women charge less for "heavy" S&M than for just spanking.  Is this saying that female prostitutes prefer “heavy” S&M, which I would think involves much more work, over just spanking?  Possibly there are those out there who have more insights into this than I do.