Report on usage of My Favorites feature

Content

Our end-user pages have the option to add an answer to My Favorites, which adds the answer to user's My Favorites page. The user can then go to their My Favorites page and see those answers that they have added. I am interested in knowing how many of our users have added articles to their My Favorites page. The reason I want to know is to determine whether that's a feature we want to retain or disable. 

Any ideas?  

thanks, Derek