I really don’t know and can find no data on the numbers. Judging by what is online there is an extraordinary presence of ‘barefoot’ and ‘minimalism’ running; there are literally 100′s of blogs, Twitter accounts, Facebook page, books, eBooks, YouTube Videos, courses etc promoting it and talking about it everywhere you go online

The rest is here:
How many are doing ‘barefoot’ or ‘minimalism’ running?