You're right, I was misreading the column header. If we assume 50% asymptomatic, then that would get me down to, say, a 2.5% chance of needing a hospital.

Which means, in the absence of drastic curve flattening measures, a 2.5% chance of half-drowning in my own lungs in a hospital corridor full of cots. Still sounds pretty awful.

The key number we're missing is how many people catch the virus, but who defeat it quickly enough that they never show up on an RNA test. We'll need antibody surveys to figure that out. The Diamond Princess had 712 positive out of 3,711, but some people were tested fairly late. So if we assume half the ship caught it, that could cut the numbers in half again.