So your race accounts for less than 3% despite 89% of all black people voting left, that seams strange.

I did not do the full math but just the ballpark numbers I entered in to my calculator says that it should account for about 11%.

* 89% according to numbers from nbc

Edit: So say I assume that every African American person I see votes left. 13% of the population is African American 89% of them actually vote left. 13% * 89% = 11% Then I simply guess on all non African American a 50/50 shot. I should then be right 50% + 11% = 61% of the time.