Why doesn't my IOstat change its output at all?

My IOstat doesn't change...at all. It'll show a change in blocks being read and written, but it doesn't change at all when it comes to blocks/kB/MB read and written. When the server sits idle...it shows 363kB_read/s, 537kB_wrtn/s. If I put it under heavy load...it says the same thing. Is it bugged out? How do I fix it? Using Centos 6, being used a primary mysql server.