) Conspiracy. Careers like computer techs, specialized maintainance, have joined plumbing, electricians, etc. as better-paying jobs that both don't require degrees and are much more often pursued by men. Pretty much everybody here knows just how expensive college can be. The gap in male-female ratios is much more prevelant in the lower income families where boys have options like those cited above and girls look to teaching or healthcare/paralegal careers that require an AA.
Please remember that a decline in percentage does not necessarily mean a decline in degrees for males; the article I linked earlier said there haven't been fewer degrees awarded to men; the women's numbers have simply increased. But don't worry, boys, the government's cut in federal aid for next school year will help cull some of those pesky females trying to better their lot in life; as the college-attending gap is widest in the under $30,000 annual income households (roughly 2/3 of those students are women for the reasons noted above), that cut in funding will hit those women students (and potential students) the hardest.