For what it's worth, I used Firecalc in this way: put in a dollar amt. as a starting point, 100% in stocks, for a 10 year period. I did this just to see what I would earn just from stocks over every 10 year period from 1871 to 1991. Years 1992 thru 2000 show as incomplete 10 year periods. While the S&P500 has 'earned' about 11 percent from 1926 thru 2000, Firecalc shows from 1871. I can see that the market goes in cycles that sometimes are bad, real bad. These periods are from 1873-1876, 1880-1890, 1901-1914, 1922-1937, and 1964-1973. Of course, the period from 2000 thru 2002 was also terrible, but firecalc doesn't show it. The financial gurus like to talk about the 1920's thru today, omitting pre 1920 market results.
So,,,, is the period 1871 thru 1920 irrelevant ? Should Firecalc not take into consideration the 19th Century?