You'll find an average, median, or "common range", and good luck hammering out your criteria. Even self-reporting would likely get you varying results from the same person by their categories of interest.
as i child i used to play a mind game with myself when i was bored. i'd think of two random things and try to find a string of associations that connect the two. i was born being a nerd, playing the wikipedia game before i knew how to read
My game was sorta the opposite. After letting my mind wander for an undetermined amount of time, I would try and backtrack as far back as I could. I didn't usually make it back more than a few steps, but finding that "first" thought was always satisfying.
I have this wonderful habit of coming to a satisfactory conclusion, only to find I've forgotten what the topic I was contemplating was. 10/10, awesome way to live life.