The true reason for people not having the required number of kids is pure exhaustion. When you need 2 or 2 1/2 incomes to pay for a household plus the regulary scheduled layoffs and various disruptions plus the all time high level of taxation, no wonder people are hesitant abt kids.
Of all the people I know--friends, family, co-workers (and I work in retail, so there are a LOT of co-workers)--the overwhelming majority who have children are white. I have a Hispanic friend who is married with a six-year old daughter and a black friend who has twins (interesting sidenote--she wanted to have her tubes tied after her twins were born, when she was age 22, and could not find a doctor who would perform the operation because she was too young. Funny, you can have an abortion much younger...). One of my older sisters has six kids. She is a stay at home mom because her husband makes some big bucks. I have a cousin with nine kids, another with six and another with four. My third is on the way. Guess what? We're all white, conservative folks.
I am not saying that minority populations are not churning out children, although I would like to know where you got your statistics from. I AM saying that there is a lot more going on with regard to childbearing than statistics can tell you.
The bottom line is this: Caucasians turned their back on building families. Latinos did not. It's not hard to figure out which culture is going to expand.
(BTW your numbers are not only wrong, but not even close to being right.)