Main evidence: Universal belief (including experts), coherence of theory, directly testable implications that I deal with on a day-to-day basis (fuel cells), lots more directly testable predictions (brownian motion, all the rest of chemistry, thermodynamics, solid and fluid mechanics...)

Let's put it this way, if I encountered the kind of evidence that would be required to cast it into doubt, I'd have to revise my belief in pretty much everything. Cartesian demon level.

Maybe 15 bits? Mostly metauncertainty.

EDIT: I feel profoundly unqualified as a mere human to be tossing around that kind of certainty, but I'm going to leave it.