Half the people are below the mean.
Only in a gaussian distribution. That's why mean is not a good indicator of central tendency for incomes - they don't usually follow a normal distribution. Half the people are by definition below the MEDIAN in ANY distribution regardless of skew or kurtosis. Median is a better indicator.
Actually, mean is the same as average. The only technically correct statement would be: "Half the people are below the median." However, I wasn't going to be picky in my cynicism.