Simplify the following text for a Grade 7 native English-speaking person.
Original: Linux distributions are also commonly used as operating systems for supercomputers : As of 2010 , out of the top 500 systems , 459 ( 91.8 % ) run a Linux distribution .
Simplified: Linux is commonly used as an operating system for supercomputers . As of November 2007 , out of the top 500 systems , 426 ( 85.2 % ) run Linux .