Looks like Newt is mainstream.
http://www.divorcestatistics.org/
Divorce statistics in America for marriage
Marriage Divorce statistics (in percent)
First Marriage 45% to 50% marriages end in divorce
Second Marriage 60% to 67% marriages end in divorce
Third Marriage 70% to 73% marriages end in divorce
First of all, it depends on whose figures you use, how many first marriages wind up in divorce.
Second of all, we’re not really just addressing divorce are we.
Third of all, why would a guy make a promise in public not to cheat on his wife, when he’s already failed on that account twice before?
What good is a new promise? He’s already shown what his promise is worth, twice.
CDC Marriage/Divorce 2009: In 2009, the marriage rate was 6.8 per 1000 population, and the divorce rate was 3.4 per 1000 population.
That means there were precisely twice as many marriages as divorces. Which could mean 50% of marriages total ended in divorce, although you can draw no conclusions about the relationship between 2009 marriages and 2009 divorces -- they aren't likely the same marriages.
My point is that if the marriage rate is twice the divorce rate, there is no chance that 50% of 1st marriages are ending in divorce, because once you throw in 2nd and 3rd marriages, your total divorce rate would be way above 50%, and the statistics set 50% as the upper limit.
A more interesting statistic might be the average number of years a marriage lasts. Another is the number of people who never get divorced (people who divorce once are more likely to divorce again, and skew the total number of divorces).
I wouldn't be surprised if the total divorce rate could hit 50%, since a person who had little fidelity to marraige could easily marry and divorce multiple times. But the statistics are tricky. For example, Gingrich is on his 3rd marriage. So HIS personal statistics is that 66% of his marriages end in divorce. If you pair him with just one faithful couple, their average is 50%. But if he divorced his current wife and didn't re-marry, you'd need two more couples to join your group in order to have a 50% success rate.