According to the Pew Research Center, "One of the biggest cross-national tests is the Programme for International Student Assessment (PISA), which every three years measures reading ability, math and science literacy and other key skills among 15-year-olds in dozens of developed and developing countries. The most recent PISA results, from 2015, placed the U.S. an unimpressive 38th out of 71 countries in math and 24th in science. Among the 35 members of the Organization for Economic Cooperation and Development, which sponsors the PISA initiative, the U.S. ranked 30th in math and 19th in science."
Essentially, the United States is in the middle of the pack when compared to other countries in science, math, and reading scores. Not very impressive when we have always been considered to be the "best country in the world." We are certainly lacking in the field of academics.
Below is a nice list showing the rankings of the countries. I knew Singapore would be up there, but I didn't realize they were so dominant in academics (they're a very wealthy country). Estonia and Slovenia surprised me, they were consistently in the top rankings for math, science, and reading. I was not surprised by Finland, I admire their culture and already know that they value education highly.
Source: http://www.pewresearch.org/fact-tank/2017/02/15/u-s-students-internationally-math-science/