Hillary Clinton and Donald Trump are well on their way to becoming their parties' 2016 nominees for president.

Among young voters, though, Bernie Sanders has more votes than both of them — combined.

The below chart comes from the Center for Information and Research on Civic Learning and Engagement (CIRCLE), which does yeoman's work in tracking the youth vote in American politics. For the purposes of this chart, "youth votes" are defined as those cast by people under 30 years old.

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Thus far, Sanders has won the votes of more than 1.5 million of them. Clinton is second and Trump trails just behind, but the two front-runners combine for just 1.2 million votes — 300,000 less than Sanders alone.

There has been plenty of focus on how Clinton's dominance among black voters has paved her path to the nomination. She won their votes as much as 9-to-1 in some Southern states and is currently winning them more than 2-to-1 in the Midwest.

But Sanders's dominance with young voters is almost as significant — at least in the percentages. So far, he's taking 71 percent of the two-candidate vote among young voters.

In pictures: US Elections 2016 Show all 15 1 /15 In pictures: US Elections 2016 In pictures: US Elections 2016 Democratic U.S. presidential candidate Bernie Sanders speaks to supporters after rival candidate Hillary Clinton was projected as the winner in the Nevada Democratic caucuses Reuters In pictures: US Elections 2016 Democratic presidential candidate Hillary Clinton takes photos with workers at her campaign office in Des Moines, Iowa AP In pictures: US Elections 2016 Republican presidential candidate Mike Huckabee, second from left, prays before lunch with supporters at Drake Diner in Des Moines, Iowa Reuters In pictures: US Elections 2016 Democratic presidential candidate and former Maryland Governor. Martin O'Malley, speaks during a campaign stop in Waterloo, Iowa AP In pictures: US Elections 2016 Democratic presidential candidate Bernie Sanders speaks, as his wife Jane O’Meara Sanders looks on, at a campaign event at Iowa State University Getty In pictures: US Elections 2016 Republican presidential candidate Marco Rubio speaks at St. Ambrose University in Davenport, Iowa Reuters In pictures: US Elections 2016 Republican presidential candidate Ben Carson speaks at a campaign event at Fireside Pub and Steak House in Manchester, Iowa. Getty In pictures: US Elections 2016 Republican presidential candidate Rick Santorum visiting supporters at a house party in West Des Moines, Iowa Reuters In pictures: US Elections 2016 Republican presidential candidate Donald Trump at a campaign event in Cedar Rapids, Iowa AP In pictures: US Elections 2016 Republican candidate Ted Cruz campaigns at Greene County Community Centre in Jefferson, Iowa AP In pictures: US Elections 2016 Senator Rand Paul speaks during a Caucus rally at his Des Moines headquarters in Iowa Getty In pictures: US Elections 2016 Republican candidate Jeb Bush speaks at a campaign event in Des Moines, Iowa AFP In pictures: US Elections 2016 Former Alaska Governor Sarah Palin introducing the arrival of Donald Trump during a campaign rally in Cedar Rapids, Iowa Reuters In pictures: US Elections 2016 A portrait of Democratic candidate Bernie Sanders at his campaign headquarters in Des Moines, Iowa Getty In pictures: US Elections 2016 Campaign badges on sale ahead of a Trump rally at the Ramada Waterloo Hotel and Convention Centre in Waterloo, Iowa Getty

Of course, as we've noted before on this blog, young voters still haven't turned out at high enough rates to make a real difference for Sanders. And indeed, through the first few contests, youth voter turnout wasn't exceptional, compared to 2008.

The good news for Sanders? That's starting to change.

On Tuesday, young voters exceeded their 2008 turnout in 4 of the 5 states — in three of those states by large margins.

The bad news for Sanders? He's no longer racking up the same margins among them as he did in Iowa, New Hampshire and Nevada, where he won their votes 5-to-1 and even 6-to-1. In Florida on Tuesday, it was less than 2-to-1. In the Midwestern states, it was about 4-to-1. And in North Carolina, it was less than 3-to-1.

Had he continued winning young voters by those massive early margins, the increased turnout among them on Tuesday could have made a difference. But it's still pretty remarkable that the 74-year-old senator from Vermont is taking so much of their votes.