People are making a lot out of two apparently remarkable data points from Tuesday's primary election in Kentucky's Senate race. Democrat Alison Lundergan Grimes, running basically uncontested, got more overall votes than Republican Mitch McConnell — and Democrats got more votes overall. (See jaws drop here, here, here, etc.)

This is not actually remarkable.

Kentucky is a red state, to be sure. But it also has a Democratic governor, Steve Beshear, elected in off-year elections (2007 and 2011). That's in part because Kentucky has more registered Democrats than it does Republicans — and has for decades.

In every single statewide primary election since 1990 (and prior), Democrats have voted more heavily than Republicans statewide. It hasn't mattered who's on the ticket or what the races are, Democratic voters have voted more. (There is one unusual year on that graph, 2008, when Democratic voters turned out far more than Republicans. That was because Republicans had already picked their presidential nominee, but Hillary Clinton was in the last throes of her attempt to derail President Obama.)

Data from the Kentucky State Board of Elections.

Grimes did get more votes than McConnell, that's true. But that's in part because she was uncontested. Republican runner-up Matt Bevin didn't come close to winning, but he got a lot more votes than all of Grimes's opponents combined. Overall, Republican candidates in the Senate race got about 355,000 votes (according to a preliminary count). Democrats (including Grimes) got about 404,000. In other words, Democrats got 13.7 percent more votes than the Republicans.

Tracking that metric over time — how many more votes Democrats got than Republicans, as a percentage — shows just how normal last night was. Over the past 24 years, there has been a smaller and smaller gap between the number of Democratic voters and the number of Republican voters. (Democratic voters don't always vote for Democrats, of course, making the comparison to Tuesday's vote a little bit of an apples-oranges thing, but not significantly.)

Again, there's that big spike in 2008. But otherwise, there's been a slow slide as Republicans start to vote in closer and closer vote totals to the Democratic majority. A majority, it bears noting, that is itself growing consistently smaller. In the 1990 primary, there were 1.2 million registered Democrats compared to 539,000 registered Republicans. By 2012, the margin was 1.6 million to 1.1 million. The percent of registered voters from each party that actually vote has also shifted, with Republicans finally voting at about equal rates.

So a tip: If you want to know who will win in November, don't watch the primary turnout. Watch the polls.