I like the chart. However, I do keep in mind what is says about it:
Average real annual return
Includes dividends, average taxes and fees. Adjusted for inflation.
The important item here is that this chart is "Adjusted for inflation". So, a 0% return means that the investment kept up with inflation. I suspect that we can add about 3% to the returns posted on the chart if we wish to remove the adjustment for inflation, or we can add specific amounts corresponding to the actual inflation numbers for each time period. A new chart created by doing this may show that while we did not keep up with inflation in the 1970s, not having been invested may have been far worse over 20 year periods.