U.S. baby boomers held their own against workers' skills in other industrial nations but younger people fell behind their peers, according to a study released Tuesday, painting a gloomy picture of the nation's competitiveness and education system.

The study, conducted by the Organization for Economic Cooperation and Development, tested 166,000 people ages 16 to 65 and found that Americans ranked 16 out of 23 industrialized countries in literacy and 21 out of 23 in numeracy. Both those tests have been given periodically and while U.S. results have held steady for literacy, they have dropped for numeracy. In a new test of "problem solving in technology rich environments," the U.S. ranked 17 out of 19.

"These findings should concern us all. They show our education system hasn't done enough to help Americans compete—or position our country to lead—in a global economy that demands increasingly higher skills," U.S. Secretary of Education Arne Duncan said in a statement.

The results show a marked drop in competitiveness of U.S. workers of younger generations vis a vis their peers. U.S. workers aged 45 to 65 outperformed the international average on the literacy scale against others their age, but workers aged 16 to 34 trail the average of their global counterparts. On the numeracy exam, only the oldest cohort of baby boomers, ages 55 to 65, matched the international average, while everyone younger lagged behind their peers—in some cases by significant margins.

In most cases, younger American employees outperformed their older co-workers—but their skills were weaker compared with those of other young people in OECD countries. By contrast, some countries are improving with each generation. Koreans aged 55 to 65 ranked in the bottom three against their peers in other countries. But Koreans aged 16-24 were second only to the Japanese.