On Wednesday, I wrote a little screed about how Iowa doesn't deserve its early primary position. I offered California instead, arguing, among other things, that it better represented the country and, of course, let far more voters weigh in. That made me wonder: How many voters actually do pick presidential nominees?

Dave Leip's great-if-not-super-modern Atlas of Presidential Elections has collected data on contested primaries going back to 1992 -- including vote totals by state for primaries and caucuses, when possible. It allows us to estimate with some certainty how many voters cast their votes for candidates. But, perhaps more interestingly, it lets us figure out which voters actually mattered -- that is, the votes cast before and after a candidate clinched the nomination.

Pulling data by state and matching it to the primary calendar gives us a decent estimate. Since 1992 (and, again, excluding sitting presidents who won re-nomination), on average 9.1 million people have voted for the winner of the nomination before he clinched (defined here as getting the required majority of delegates). The high was the nomination of Barack Obama, which only happened at the very end of the process and which saw massive turnout. Most of the time, the nominations were clinched in March, as was the case with the lowest total: former Kansas senator Bob Dole, who won the nomination after only about 5.1 million votes in 1996.

In case it needs to be said, that's a very small subset of those eligible to vote. Using data on the voting-age population from the Census Bureau, we combined the voters from both major parties in 2000 and 2008 to see how much of the possible electorate actually picked the nominee.

But back to Iowa. In the process of tallying the votes, we flagged when states got to hold their contests before the nomination was clinched. (This is trickier than it sounds; several states hold caucuses and votes, for example.) On the map below, darker-colored states more frequently held their elections prior to the nominee clinching. Voters in nine states got to weigh in while it still mattered less than half of the time.

So let's revise the argument from yesterday a little. Let's move up Pennsylvania or New Jersey or West Virginia or Arkansas for a few cycles. Give them more say in who the nominee will be. We can skip that for 2016, of course, both because the deadline is looming and, frankly, I think we can guess which Democrat Arkansas will vote for.

The dates each nominee clinched: Clinton, June 2, 1992; Dole, March 19, 1996; Gore and Bush, March 14, 2000; Kerry, March 16, 2004; Obama, June 4, 2008; McCain, March 4, 2008; and Romney, May 29, 2012.