I had seen the similar results when I try to search for popular keywords like college. The thing I noticed is that there are not a lot of people searching for college exact match (they usually search for college + information about the education or location).
I think you have the same problem as I did. The easiest way to deal with it is to use the SEOMoz Keyword difficulty tool, because that way you will get clearer view of the whole picture. Also I recommend going for longer and more specific keywords since this will ensure more conversion oriented traffic from the search engines 
Hope this helps you. If you have any other questions, please do not hesitate to ask, but make sure you mention the market your are targeting
