Bigfoot, UFO's and Ghosts

As 2 people believe in all 3 we can use subtraction from the other categories.
11 People believed in UFO's and Ghosts -2 =9
6 people believed in Bigfoot and Ghosts -2=4
4 people believe in Bigfoot and UFO's - 2=2

21-2-2-4=13 people believe in bigfoot.
42-2-2-9=29 people believed in UFOs.
45-4-2-9=30 people beieved in ghosts.
13+2+2+4+29+9+30=89
89 People believed in at least one of Bigfoot,UFO's or Ghosts