VOO (SP 500 index) has a current dividend yield of ~1.6%, ignoring that it was likely higher yield in the 80s and honestly much of this time frame, you use the

VOO (SP 500 index) has a current dividend yield of ~1.6%, ignoring that it was likely higher yield in the 80s and honestly much of this time frame, you use the rule of 70 to determine it would take about 43 years (70/1.6) to double from just dividends. Of course this ETF (the index did exist) didn't exist in the 80s, and you increased the valuation numbers much more due to inflation which was double this dividend rate for all of this period. Additionally somewhere in there, the US economy grew a lot in this time period.