https://www.spglobal.com/spdji/en/documents/research/research-what-happened-to-the-index-effect.pdf
The S&P 500 had 715 additions and 711 deletions between January 1995 and June 2021, averaging around 27 constituent adds and drops per year 投资指数或者大盘的好处就是不需要担心你选择的TOP 10在10年后会不会连TOP 100都进不了，指数自动帮你take care好了，self cleansing
