As Republicans try to settle on a candidate to face President Obama in November, it's mostly older, white, Christian voters who are casting their ballots.

Tristan Spinski/Corbis

he United States has roughly quadrupled in size since 1900, when the population was just 76 million. Today, our nation comprises roughly 312 million people in a lively melting pot of races, religions, and opinions. But "you would not know any of this looking at who is voting in one of the strangest presidential primary campaigns in history," says Timothy Egan in The New York Times. In a very competitive race to pick a Republican nominee who will face a vulnerable Democratic incumbent, only a small fraction of "old, white, uniformly Christian" Americans are showing up to vote, and they look "much closer to the population of 1890 than of 2012." Here, a by-the-numbers look at just who's picking the GOP nominee:

9
States that have held GOP caucuses or primaries so far

28 million
Registered voters of all parties in those nine states

3 million
Voters who have participated in these nine Republican contests

89
Percent of registered voters who have not voted in the GOP contests

63.7
Percent of U.S. population that is white

88
Percent of U.S. population that was white in 1900

99
Percent of 2012 Iowa caucusgoers who were white

89
Percent of Iowans who are white

98
Percent of South Carolina primary voters who were white

66
Percent of South Carolina residents who are white

66
Percent of South Carolina primary voters who were evangelical Christians

72
Percent of South Carolina primary voters who were 45 or older

3
Percent of Nevada's registered voters who participated in the state's Feb. 4 caucuses

5
Percent of Nevada caucusgoers who were Latino

26
Percent of Nevadans who are Latino

14
Percent of Florida GOP primary voters who were Latino

23
Percent of Floridians who are Latino

78
Percent of Florida primary voters who were 45 or older

59
Percent of Florida voters in the 2008 general election who were 45 or older

47
Percent of GOP voters nationwide who are happy with their candidates, according to a PPP poll earlier this month

73
Percent of Democrats who are happy with President Obama as their candidate

Sources: Census Bureau, Demographia, Google Elections, New York Times, RealClearPolitics, Talking Points Memo