(CNN) – Suicide is the number three killer of adolescents, according to the world health organization and depression is a key factor in suicide deaths.

Now, a new study finds that there has been a significant rise in major depression among young people in the US. And data indicates that trend may be strongest in teenage girls

The prevalence of major depression is rising for young people but especially for girls aged 12-to-17.

A study published in the journal “pediatrics” examined government data from more than 172-thousand adolescents and more than 178-thousand young adults aged 18-to-25.

Researchers found that cases of major depression among all adolescents rose from about nine-percent in 2005 to about 11-percent in 2014.

Among young adults, they rose from about 9-percent to about ten-percent. But the biggest increase was among the group that already had the highest rates of depression teenage girls. Data showed the prevalence of major depression among that group jumped from about 13-percent to about 17-percent in 2014 over the same time period.

The increase among boys was lower and moved from about four-percent to about six-percent. Researchers noted that there was not a corresponding rise in the proportion of adolescents receiving treatment.

They say more research is needed to understand why depression is increasing fastest among teenage girls. And that more needs to be done to improve access to depression care for all young people.