Check it out, he's convinced that "a large percentage" of parent wish they'd never had kids, but he himself has no clue, as he's childless. I would say that almost all parents I know would do it all over again if they could.
My observations are that there are both happy and unhappy parents. Count your blessings, and don't worry about the percentages. I think you may be farther out on a limb by saying "almost all", but I'd agree that most are glad they had kids.