Math teachers tend to be liberal too, because we can see through the absurdity of the idea that most current teachers were Vietnam-era draft dodgers. If you were 18 in 1971 (55 years ago), chances are very good that you retired back in the aughts. Also, your reductivism ignores women teachers (a little more than 60% of middle and high school teachers on average).
But keep on flogging bad data: it's a good brain exercise for the rest of us!