Increasing. A close answer to your question is cited by an article "Prevalence of open-angle glaucoma among adults in the United States", authored by Friedman DS, et al. Arch Ophthalmol. 2004. "The overall prevalence of OAG in the US population 40 years & older is estimated to be 1.86%, with 1.57 million white & 398, 000 black persons affected; the number with OAG will increase by 50% to 3.36 million in 2020"
Everyone. Anybody at any age, but especially in the older age group, could get glaucoma. That is why your ophthalmologist will test you for this condition on each examination.