American companies are spending more on compensation than they have in years, but you probably have to be top performer to expect a big raise. 

A study by Aon Hewitt, an international human capital and management consulting company, predicts that base pay for salaried exempt employees increased by 2.9 percent in 2015. That means base salaries will at least be keeping pace with the growth of the U.S. economy. However, variable pay increases, which includes bonuses and other incentives, will increase 12.9 percent. 

Companies have long budgeted more money to bonuses than across-the-board pay raises, but the disparity between the two has become much larger in recent years. For instance, a similar survey in 1996 showed that salaries rose by 3.9 percent while bonuses rose by 7.5 percent.