I think the relevant table is on page 13 "COVID-19 hospitalizations in unvaccinated and fully vaccinated individuals in
Washington state by age group, February - December, 2021"
It shows that 79% of hospitalizations in the state are unvaccinated people and that of those, 3,000 are under 34, 11,000 are between 34-65, 7,000 are over 65.
So it is indeed largely elderly unvaccinated in the hospital.