I linked to this report the other day. I think it was in this thread, but it's easier to link it again than go back and find it:

http://pewsocialtrends.org/files/2011/05/Is-College-Worth-It.pdf

I know there's a lot of information there, but you will find the calculation on page 83 and the graphs on pages 88 & 99 particularly germane. Also, the bar graph on page 36 that shows 86% of college graduates polled who said college was a good investment for them personally.

Here's more recent data from Planet Money:
http://media.npr.org/assets/img/2011/04/01/Unemployment-by-education.jpg?t=1301669694&s=51

And the article from whence it came:
http://www.npr.org/blogs/money/2011/04/01/135036740/6-ways-of-looking-at-unemployment

If you do not agree with my stance that college is important, you have the right to ignore me and find data to support your own stance. So do my students. If you think money is a terrible reason to go to college, it's not my favorite either, but my students need to make an informed decision on something that may have such a big impact on their futures.

For the record, I was teaching stance and evidence and had presented "stance" as being somewhere between opinion and hypothesis when I showed a slide that said, "Stance: College is important". The evidence I presented clearly showed that most people with a high school diploma had jobs and that some people with graduate degrees did not find their jobs interesting.

My students had been learning mean, median, and mode in math class, and we talked about the fact that there are always people in each category who make more than the average and people who make less. For example, a kid called Bill Gates got into Harvard, but decided he'd rather start a company called Microsoft than graduate. My students came up with their own examples of relatives that make a decent living without a college degree, and some can already recite the College Is Important speech they got from their own parents.