这样一组数据不知道可以解答你的疑惑吗：
May 2014 employment: 145,920
2012–22 projected growth: 27 percent (faster than average)
May 2014 median annual wage: $51,930 (higher than the $35,540 median wage for all workers)
Education typically required at entry level: Master’s degree
May 2014 top-employing industries: General medical and surgical hospitals, home healthcare services, individual and family services, nursing care facilities, outpatient care facilities.
Note: Employment, wage, and industry data exclude self-employed workers.
数据来源于：美国劳工统计局
