The suicide rate among middle-aged Americans rose to 28% in a decade

Among adults 35-64, white people and American Indians saw the sharpest increases from 1999 to 2010.

Among American Indians, suicides increased 65% from more than 11 per 100,000 to almost 19 in that decade

Suicides by white people increased 40%, from 16 per 100,000 to 22.

Experts are unsure about what caused the increase in suicides to be so disproportionately steep among Native Americans and white people, during a period which spanned the recession.