WAC2013's listing is correct though I continue to wonder why so many people still have the feeling that approval for approved shoreside employment is "rare" - there are, have been and continue to be many approvals granted and right now with sailing employment tight that is likely to continue.
The "10 year number" that seems to be thrown around by some must be the four 4 as a Midshipman USNR you serve while attending the Academy and the minimum of six (6) that you must serve following graduation if you do not go active duty.
Further the "1/3rd" going active duty number that kpmom2013 is citing is reflective of the past ~4 years graduating classes.
Just my thought on your post - If your son or daughter is certain or nearly so that they wish to go active duty, vice also consider a career in the maritime industry, especially if they are thinking of a pursuing a career that is not in one of the Military Branches with a maritime focus (Navy, or Coast Guard), they may well be better served pursuing another route to obtaining their commission. As has been cited in numerous threads on this subject the USMMA is primarily a Maritime School and it's primary purpose and focus is to train Mariners, as such if their interests are not in those areas, a young man or woman is likely to find the majors and experience they receive training and education in at USMMA far less interesting or useful than someone who wants to be a Merchant Mariner, Naval Officer, or Cost Guardsman. That said, they will of course receive a fine education and have both those and other opportunities to serve upon graduation.