Return of ETF's exceeds expectations by far, why?

Hi Mintos!

The page on ETFs gives an estimate 5.3% return on investment for the ETF mix on https://www.mintos.com/nl/etfs/overview/

Last year, the return was a lot more (around 25% I guess, now profits have shrunk somewhat).

Can you reflect on the ROI of the ETFs, is the estimation just too low or was it an exceptionally good year?