Nevada has the sixth largest percentage of inmates in the nation who are over the age of 50, a report released today by the American Civil Liberties Union claimed.Defining prisoners over the age of 50 as elderly, the report says states could save an average of more than $66,000 per year by releasing them. The United States currently imprisons 246,600 Americans 50 and older, a generally low-risk population that costs much more to keep locked up than younger prisoners, according to the report. It costs $34,135 per year to house an average prisoner, but $68,270 per year to house a …