China is experiencing a supercomputing boom.

For the past two years, the country has been home to the world’s most powerful supercomputer, the National University of Defense Technology’s Tianhe-2 machine. But China’s prowess at building supercomputers is becoming widespread.

China now hosts 109 of the high-performance computing systems on a widely watched list of the world’s most powerful supercomputers that was released Monday. The country had just 37 machines on the list only six months ago.

The U.S. remains home to the largest number of supercomputers on the list, but with 200 machines, the U.S. tally has fallen to its lowest level since computer scientists began compiling the list, called the Top500, back in 1993.

The U.S. is slipping on the Top500 list even as the country performs an unprecedented build-out of high-performance computing. Over the past decade, companies such as Alphabet Inc.’s Google, Amazon.com Inc. and Facebook Inc. have spent billions building massive data centers that operate as supercomputers for the Internet. These systems, however, aren't optimized for the type of calculations that the Top500 list’s benchmarks test for.