More than 45 million Americans — roughly one in five — suffered from some sort of mental illness in 2010, according to a new government survey.

Those numbers represent a very slight increase in mental illness rates from 2009, but numbers overall have remained steady. For the purposes of the survey, “mental illness” was defined as any diagnosable mental, emotional, or behavioral disorder regardless of whether or not it impairs someone’s day-to-day life.

Nearly 30 percent of young adults aged 18 to 25 had such a disorder. The estimates for adults between the ages of 26 and 49, and those 50 and over, were 22.1 percent and 14.3 percent, respectively.

Women are more likely than men to be affected, but researchers note mental illness among men is increasing — it rose one percent between 2009 and 2010.

Demographically, people of mixed-race had the highest percentage of mental illness, and Asians had the lowest. The survey also reports that those below the poverty line had significantly higher rates of mental illness than those with larger incomes.

In a news release accompanying the report, Ileana Arias, PhD, principal deputy director of the Centers for Disease Control and Prevention, said, “Today’s report issued by SAMHSA provides further evidence that we need to continue efforts to monitor levels of mental illness in the United States in order to effectively prevent this important public health problem and its negative impact on total health.”