The turnover rate among the nation’s CEOs fell 10 percent in March, according to a monthly report by Challenger, Gray & Christmas Inc.

After reaching a 17-month high of 132 in February, departures dropped last month to 119.

The first quarter, however, saw an overall 10 percent increase in CEO turnover, with 340 announced departures. That’s compared to 309 exits through the first quarter of 2009.

In March, the government/nonprofit sector experienced the highest turnover among all industries, with 22 CEO changes. For the year, chief executive turnover in the health-care sector led all industries with 56 departures, 21 of which occurred last month.

The given reason for nearly one-third of all exits was resignation, which accounted for 102 departures for the year. With 95 exits so far in 2010, retirement was the second leading cause.

Fifty-seven CEOs stepped down into other positions, most of them staying with their companies in some capacity. New positions in other companies were found by 27 executives. And 26 of the CEOs leaving their posts this year were only in place on a temporary basis, and were being replaced by their permanent successor.

“As the recovery takes hold, boards are likely to become increasingly impatient with leaders who fail to achieve results, said Challenger, Gray & Christmas CEO John Challenger. “Each missed opportunity is a check against that executive.

“We are also entering a period of increased retirements, which may be resulting from CEOs wanting to get out from pressure of recovery expectations. It could also be that we are starting to see the impact of the aging Baby Boomers on the ranks of CEOs.”

In 2010, 95 CEOs have announced their retirements, up from 46 in the first quarter of 2009.