Nobody really knows how many deaf and hard of hearing people are in the United States.  At best, an estimated 36,000,000 (2000 Census data)  people have a hearing loss. Of the 36 million, about 5% of them have a severe loss and another 3% a profound one.  The percentages increase along with the age bracket. 
50% over 50 years have some hearing loss
85% over 85 years have some hearing loss