Here's a link from a NYU Professor https://pages.stern.nyu.edu/~adamodar/New_Home_Page/datafile/histretSP.html
Ed McQuarrie talks the REAL History of Stocks and Bond performance.
https://www.morningstar.com/funds/what-doubters-get-wrong-about-6040-portfolio
What the 60 percent stock portfolio and the 40 percent bond portfolio helps your portfolio