In the perks of being a wallflower, how many times had charlies aunt molested him?

I reread this book for the first time since the first time i read it over a year ago, and picked up on something i totally missed the first time: His aunt Helen molested him. He says something the book along the lines of him dreaming about watching SNL with his brother and sister, but his aunt helen was doing what sam just did to him. Does that mean that she molested him once, or she molested him on more than one occasion?