Overall compensation for the nation’s top executives rose more than expected last year, but the rate of increase was the lowest in six years, according to a study released Tuesday.

The Corporate Library, an independent corporate governance group, said the median pay raise for the 1,864 executives who received one in 2007 was 7.5%. Total actual compensation for chief executives at 2,701 companies - including those with pay cuts or no change - was a median $2.05 million.