Well, your "rough calculations" are a little off... as you can see from the table below, since 1945 the dems have had control both the house and the senate 48 out of the last 62 years, including having a democrat President for 20 out of those 48, as opposed to the repubs who have had both the house and the senate for a meager 12 years out of the last 62, with a repub President a pathetic 4 of those.
Now you tell me... who's been running the country for the last 62 years? Who's had the opportunity, or not, to get things done? The dems man, period. The repubs have been at the MERCY of the democrats for years, and still are. As much as I hate to admit it, the minuscule amount of time the repubs DID have to do something, they squandered it like a bunch of sissy sons a bitches, or maybe better described, plain old business as usual, status quo, stinking politicians.