While high fashion designers showed off their 2015 fall collections at New York City Fashion Week, those in the know went to Las Vegas for the fashion and retail world’s largest trade show, Magic Market Week. This year’s conference saw more than 80,000 attendees, and featured an entire new section showing off yoga, Pilates, activewear, and athleisure apparel. While apparel sales rose just 2% in 2014, activewear clothes sales jumped 10% to more than $33 billion. That’s because yoga clothes and leggings aren’t just being worn to the gym anymore. In 2015, only one in ten women says she uses…