America is failing its kids when it comes to early education.

One of the best practices that the Organization for Economic Cooperation and Development (OECD) has identified for educational success is an early start, and in this arena, the United States falls “significantly behind.

For children between the ages of three and five, the U.S. falls 34th out of 36 countries. Only 67 percent of that age group is enrolled in early education programs (a group including preschool and kindergarten). Of the OECD nations, only Turkey and Switzerland have lower stats, and Turkey’s numbers include its massive refugee population.

The OECD is an intergovernmental economic organization, with 35 collaborating countries including the U.S., Canada, most of Europe, and a few more developed nations worldwide. It was founded in the 1960s to compare policies and results among its members, and to identify what practices work best across broad contexts.

One of the things that it monitors very closely is educational standards. Enrollments, graduation rates, future earning potential, all of those details.

“Giving all children access to high-quality early education and care will lay the foundations for future skill development, boost social mobility and support inclusive growth,” said Gabriela Ramos, OECD chief of staff, in a statement that accompanied the release of their new report.

Many, but not most, U.S. states are increasing their access to free early education, but not at a rate equal to the rest of these high-earning developed countries. The U.S. still spends less than one half of one percent of its GDP on preschool, half of the OECD average of 0.8 percent.

If this contributes to the U.S.’s low ranking in the OECD’s PISA (Program for International Student Assessment) exams, which were administered to over half a million 15-year-olds in 2015, it’s not a hard correlation. But Singapore, which scored top in all three categories tested (science, math, reading), begins public school at 4 years old.