Pretty remarkable. 541 million dollars spent by Super PACs so far this election cycle...20 times what they spent in 2008, prior to Citizens United...and 289.5 million of that was spent in opposition of the President. Not for Romney, that was only about 50 million...but in opposition of the President.
ETA: Yeah...clearly they benefit both...or something.
Per your numbers: $541m total spent. $289.5m spent against the dems, meaning $251.5m spent against the GOP.
Both use them and, presumably, both consider the money well spent.