I've looked more into it after Mr. Muppet posted some charts...
I found that the DARTs has been rising since late 2019...a few months before the Pandemic and then there's been a decline since the Pandemic. For example, Interactive Brokerage is down -12 % in April following record gains in March and they point the finger at Covid-19 for their decline.
Yet, they go on to say a year to year comparison for the month of April (as in April 2020 versus April 2019)...April 2020 was still 27% higher.
The question now is why were they dramatically rising for a few months prior to the Pandemic ???
wrbtrader