As you can see, salaries have been grew steadily from 1985-2000 when they started to level off. There was then a slight decrease in the late 2000s. Interestingly, there is a big uptick in average salary this year, I'm not sure why.
Note that the red line is the real average salary. If NBA salaries were merely keeping up with inflation this would be a straight line from 1985-2013. Given its slope you can see that for most of the past 28 years NBA salaries have been growing faster than inflation.