Among the end-of-year lists I noticed at the close of 2014 was The Top 10 Charts from the Economic Policy Institute. Each of the charts describes growing economic inequality in a different way, some of which are a bit complicated or nuanced -- though all are important.
I found the one shown above to be the most compelling and easy to understand. (Go to the article itself for the interactive version of this and nine other graphics.)
It really is this simple: workers keep producing more, but they do not receive more. That wealth is going somewhere, and our democracy really depends on figuring out how to make sure some of it stays with the people who create it.