In an infectious disease context, 20 percent is a massive number. We're seeing 20% and higher in many localities, but that's as a function of confirmed cases (and there are many unconfirmed cases out there) - but also we know anecdotally that there are patients requiring ventilators for moderate to severe pneumonia that have not yet been confirmed as Covid cases (but almost certainly are) - so you have to consider those as well.
The real incidence is probably between 5% on the low end and 15% on the high end (with higher incidence in the older demographics). But those are still massive numbers if overall volume is significant.
In comparison, H1N1 was hospitalizing at a rate of .45% (less than half a percent) and flu is about half of that (.25%).