U.S. Stock Market Returns – a history from the 1870s to 2024

Fair point. Given that these values are adjusted for dividends/inflation, at least that means your retirement savings slightly outperformed the rate of inflation over 20 years.

Not a great outcome for retirement savings, but better than leaving the cash under your mattress.

Also note that the worst case 20-year return was from 1901 - 1920. If we only look back until 1990, the worst 20-year return period was +3.3% per year (rolling period ending in 2018)