That percentage could be different according to nationality.
For example, here in Australia, there are plenty of girls (especially the surfie/beach type) who don't think twice about walking around barefooted. You can pick them straight away: scruffy hair, scorched skin, natural but beat-up feet. And a lot of them that I've met have this "I'm not ticklish but I don't like my feet touched" attitude; unfortunately I have found out that some of them are telling the truth about their (non-)ticklishness.
Maybe the constant barefoot walking and the salt have changed their skin composition somewhat?