"Between 1692 and 2018, stock prices increased at an average rate of 1.87% per annum before inflation and 0.36% after inflation, and with reinvested dividends averaging 5.04% per annum, investors received a total return of 6.62% per year. £1"

Now, that being said, during this time frame, clearly the UK is also a western superpower, and after a certain point in time the UK & US stock markets probably have a very strong correlation with the rise of electronic trading/risk management.

For another example of an older equity market, we might look to Japan, which has had a negative rate of return: https://www.afrugaldoctor.com/home/japans-lost-decades-30-ye...

That being said, as we see in that article the monthly $833 purchase DCA still gave a positive return over 30 years.