How to generate "most common/popular zoo animal" list

I’m putting together a trivia contest for an upcoming family reunion. Something I’d like to have is some kind of vaguely objective, or at least authoritative, list of the most common/popular/iconic zoo animals. Ie, it would go something like:

  1. Lion
  2. Giraffe
  3. Elephant
  4. Hippopotamus

49. Eagle
50. Water Buffalo

or what have you. I though some zoo society might have some list already (based on request, or occurences, or something) but some googling failed to find one. I also figured I could look through several zoo sites, find lists of all their animals, and then rank them by number of google hits when I google that animal and “zoo”, but that’s a lot more work.
Anyone have any bright ideas?