Part of the problem is that each profession isn't scaled to how many people are in it. "47-5031 Explosives Workers, Ordnance Handling Experts, and Blasters" had a total employment of 7,970 in 2012, but there were 1,353,020 people employed as "25-2021 Elementary School Teachers, Except Special Education"
http://www.bls.gov/oes/current/oes475031.htm http://www.bls.gov/oes/current/oes252021.htm