"add to favorites" question
 

sorry if this is a dumb question...but I shall ask anyways... I have always noticed that in my stats there is a "Add to favorites (relative indicator)" section.. now I have never really paid any attention to this as I have never added a site to my favorites, and frankly...don't even know how
But, anyhoo....most of my sites average around 60-70% of this number that has no meaning to me...but my main site has 109%
so this leaves me very confused...this is a number I don't take into account for anything---and at the same time impossible...
can someone explain this to me(I'm sure its something simple and dumb...but since I don't know...will someone just clue me in)
Thanks