That chart was done only as to what could happen if the rates of infected cases continue on at the current pace. It was not a prediction by any means.
With all of the current self quarantine currently taking place one would think that the rate of infection will start to taper off soon and those numbers may be way too high.
However with the lack of testing in the US it is hard to really know what the current accurate numbers are and that increases in the infection numbers are already baked in for some time to come.
covidtracking.com currently shows Iowa with 105 cases as of March 23.
https://covidtracking.com/data/#IA
They also list 3,325 hospitalized out of 42,164 positive cases.
Another site shows NYC with 10,764 positive cases with 99 deaths. Out of these 1800 are hospitalized with 450 in ICU. That is 16.7% hospitalizations and 4.18% in ICU in New York City
Edit: From above total numbers in the US that would be 7.88% cases hospitalized.