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"