In the US, I assume? Also, note that app stores aren't the only revenue, and precisely because the web does not work as well on ios devices, this number will be slightly biased in apples case.
It appears to be globally, though it depends on what you count exactly (65% of the total revenues, I was off sorry, but 80% of all subscription revenues). The reality is that the hundreds of millions in poorer countries with Android spend peanuts compared to rich countries.
https://www.businessofapps.com/data/app-revenues/
But whatever the exact number, the point stands. In most cases, not supporting iOS is a silly business decision.
But whatever the exact number, the point stands. In most cases, not supporting iOS is a silly business decision.