A nugget of data from the midterm exit polls attracted some attention this week. Preliminary exit polls indicated that 37 percent of the electorate was over the age of 60, prompting news articles and Twitter consternation about the apparent imbalance in representation.

There are two important things to note, however. First: That the 37 percent figure was later revised downward. Final tallies put the percent of the electorate that was over 60 at closer to 34 percent. Second: People who are 60 years old in 2014 were born in 1954, at the height of the Baby Boom. In other words, we should expect that the percentage of voters that is in that age range comprises a bigger share of voters.

We touched on this in October, looking at Census data to project how the electorate might expand. This is how the population is expected to evolve over the next 50 years.

We can see it more directly in a look at midterm exit polling over the past 36 years.

Someone who was 25 in 1978 was born in 1953. Younger people used to comprise more of the electorate. Then they got older.

And for Democrats, that's bad news. If you apply the party split of each exit poll age group to the percentage of the electorate -- a rough but illuminating calculation -- you can see how politics have shifted to the right. (The blank space at the top of the chart is a function of rounding.)

In 1978, 20 percent of the electorate was over 60; half of them backed Republicans. In 2014, 34 percent of the electorate is over 60; 55 percent of them backed Republicans. Those number have moved logarithmically, combining more people with a shift to the right.

A colleague of mine (a Boomer, I'll note) once compared the Baby Boom generation to a snake swallowing a pig. Once it has worked its way through, things will return to normal, relatively speaking. The most common age in America right now is 22. Those people will be voting for the next 40 years, and so far have been voting pretty blue. But for now, America's still digesting that pig.