How do you explain this?

Okay, I've asked this question already, but not I've got all my sources laid out.

According to this website, http://nces.ed.gov/programs/digest/d13/tables/dt13_104.20.asp, only 40% of people between 25 and 29 have Bachelor's Degrees.

According to this website, http://nces.ed.gov/programs/digest/d13/tables/dt13_326.10.asp, only 43% of people who go to college graduate in 4 years, and only 62% graduate at all. 43*100/62 is about 69. Therefore, of the people who did graduate, only 69% graduated in 4 years. 69% of 40% is about 28%.

Therefore, only about 28% total should have had their Bachelor's Degree by 21 or 22.

Now, I understand that these statistics also include people in poverty, but that leads me to talk about this site, http://kff.org/other/state-indicator/poverty-rate-by-raceethnicity/. Only 15% of people are in poverty. 2800/85 is about 33, so only 33% of people not in poverty should have had Bachelor's Degrees by 21 or 22. Why does this not seem to be the case?