The number of chief executive officers who left their companies in July fell to its lowest level of the year, a Chicago-based outplacement consultancy said. Eighty-three leadership changes were announced during July, compared to a June total of 99 CEO departures, down 16.2 percent from June, Challenger, Gray & Christmas Inc. said Wednesday in a release. Challenger said it has tracked 692 CEO changes in 2012, which is 2.5 percent lower than the 710 CEO departures recorded for the same time period in 2011. For the year, the healthcare industry reported the highest turnover, with 140 CEO changes in 2012, including an industry-leading 13 in July, Challenger said. The government-non-profit sector experienced 11 CEO changes last month, while computer and financial firms each announced 9 departures. In July, 30 CEOs resigned, which was the most cited reason so far this year, with Challenger saying 205 resignations were tendered. Retirement follows with 143, of which six came in July. To date, 114 chief executives, including 15 in July, stepped down but usually remained with their companies as a board member or in some other corporate-level capacity.