HOUSTON, May 7 (Xinhua) -- The number of job openings rose to 7.5 million on the last business day of March, the U.S. Department of Labor reported Tuesday. The job openings rate was 4.7 percent, with the number increasing for total private and little changed for government. The number of hires was little changed at 5.7 million in March, and the hires rate was 3.8 percent. The hires level was little changed for total private and for government. The number of total separations in March was little changed at 5.4 million, which is a 3.6 percent rate. The number of total separations was little changed for total private but decreased for government. Large numbers of hires and separations occur every month throughout the business cycle. Net employment change results from the relationship between hires and separations. Over the 12 months ending in March, hires totaled 69.3 million and separations totaled 66.6 million, yielding a net employment gain of 2.7 million.