Bad charts make for bad analysis. Looking at these charts, I see a buildup of debt as age increases into middle age. I doubt the charts would bear out if taken further back in time. You have to remember that Reagan greatly increased the decline, so all charts should probably go back to pre-Reagan (probably starting at pre-Ike). If you can ignore racial factors (which we're still trying to overcome and the article's analysis doesn't cover), the late 50s was probably the high point.