In 2012, Democrats won 59,649,982 of all votes cast for House candidates (49.16 percent) while Republicans got 58,284,285 (48.03 percent). And yet, Republicans kept their House majority as Democrats netted just 8 seats.

How rare, historically speaking, is one party winning the House popular vote and not winning/holding the majority in the same election? Pretty damn rare, according to new data from the indispensable Vital Statistics on Congress.  The last time such a split occurred was way back in 1946, which also happens to be the first election for which Vital Statistics has, well, statistics.

Where do all the elections between 1946 and 2012 fit when it comes to the relationship between the total vote cast for House and the number of seats each party holds after the election? Sunlight Foundation's resident genius Lee Drutman has the answer -- and he even built a chart!

Let's check out Drutman's chart first. The dotted line running at a 45 degree angle across the chart shows "what an election that perfectly translated vote share to seat apportionment would look like," according to Drutman.

Image courtesy of Sunlight Foundation

What's clear is that Democrats regularly outperformed -- in terms of the House seats controlled -- their vote share, particularly in the mid 1970s.  Republicans not so much, as their vote share and their number of seats have tracked far more closely over the decades. (One fascinating anomaly: In 1994, Republicans should have actually won MORE House seats than they did based on the total votes cast nationally.)

Concludes Drutman about 2012: "While such a reversal of electoral fortune is unusual, a significant disparity between a party’s seat share and vote share is not.  Historically, Democrats have benefited from distortions of apportionment much more than Republicans, especially during the 1960s and 1970s."