I figure is the about the same as I think. Numbers, I don't have. But unlike most if not all on this site, I think this country has been moving left beginning with FDR. Slowly, but surely.
As for numbers, elections indicat which way folks want to go. When one party goes too far one way or the other, the people elect the other party. Little steps are fine, gigantic steps meets with opposition as it take those unwash folks in the middle out of their comfort zone. Perhaps the best strategy is slow, but steady. The problem with that is you have quite a lot of folks who want everything right now.