20,230 is what is reported by the US Government: http://www.bls.gov/oes/current/oes412011.htm http://www.bls.gov/oes/current/oes412011.htm So the number stated

20,230 is what is reported by the US Government: http://www.bls.gov/oes/current/oes412011.htm http://www.bls.gov/oes/current/oes412011.htm So the number stated is the mean, not the mode or median.