Obvious. But we typically see figures in terms of means and medians when in reality, the difference between the person who makes the most and the one who makes the least can be significant.The chart b shows the spread for major occupation groups, for several decades. Imagine you randomly select 50 people from each group, and this is what their annual income probably looks like.The data for 2000 and earlier comes from the decennial census, and the data for 2010 and 2014 come from the American Community Survey.As you progress through time, you’ll notice the distributions of income spread out more. This is especially obvious when you switch between 1960 and 2014. With the exception of lower paying jobs in areas such as food preparation and cleaning, it looks like there’s more opportunity to earn a higher salary (among those who have jobs at least).
See the wonderful graph: Shifting Incomes for American Jobs | FlowingData