Funny though that you are trying to go back that far as we are talking about this year's tournament. The last 6 years is a much better measurement than what happened 25 years ago.
Not to mention that using your math of 95% with 12 in the last 6 years you would need to have no others in the last 60 years to make your statement correct. Pretty sure past champions included Loyloa-Chicago, UTEP, Marquette, Villanova, Georgetown, U-Conn, UNLV, La Salle, San Francisco etc.
In other words, you were completely wrong.