STU, you read that right. But that's number's rounded off--it's actually higher. 15 pregnancies x 9 months per pregnancy = 135, which is 11.25 years. 11.25/40 (her age) = 28%+. Even if you assume she's nearly 41, that's 11.25/41 = 27%+.
The number that I found most surprising--other than the fact that they have 17 @#$%ing children, is that they go through 6 gallons of milk a week. My family only has four in it (for the moment--will be going to five sometime in the next two weeks), we're not that heavy of milk drinkers, and we still go through a gallon a day. 19 people (especially with most of them being children) would typically be going through at least 16, not 6, gallons a week! Maybe it's a typo. After all, the article says they have 17 kids, but in the paragraph where it lists all their names, there are only 16 listed...