The wiki page says the Nasdaq-100 started in 1985? Where are you getting your 1972 data from?
There's SOXX, which is a cap-weighted semiconductor ETF and SOXL which is a 2x leveraged version of SOXL.
There's a Discord channel called EA/LW Investing with about 150 people. I don't have permissions to generate invite links, but if you DM me your Discord username, I can ask someone to you add if interested.
Coincidentally, I made an app to do exactly these types of historical comparisons of returns, with much greater fidelity.
Input ^NDX and ^GSPC (Nasdaq-100 and S&P500 respectively) as the input tickers. These are Yahoo Finance's codes for those respective indices. Alternatively, you can input QQQ and SPY, which are ETFs that track those indices but there will be less historical data since ETFs come after indices.