Let’s say you’ve polled your customers and now have a spreadsheet full of data from which you need to glean insights. There are complicated tools that can do this, such as IBM’s SPSS ...

The gray line in the chart above, labeled "1980," shows the change in income from 1946 to 1980. Below, you can watch the change across every 34-year period starting with 1946-1980 and ending with ...