"Thats What I Want For Christmas"

With Christmas being just two more months away from now, I was thinking today about what the girls have to say of this song on their Christmas album, that they were blown away when they learned that no one around them had ever heard of it before. I had never heard of it before they did it either, so my question is, who sang it first because obviously someone had to have done it before them in order for them to even know about it. God bless you and the girls always!!! :) :) :) Holly