So out of 600 people in your school, nobody plays Blockland but you? How does that surprise you? There are 21000 Blockland players, but only about 15000 are active and in America. There are 310000000 million people living in America. Do the math
310000000 divided by 15000 equals about 20667.
If the math is correct, then only about 1 in 20667 Americans plays Blockland, and there are 600 people in your school.
Still surprised?