vTaskGetRunTimeStats();

Hi everyone i have one doubt
When am running my program to get the result of this function vTaskGetRunTimeStats();
am getting excecution time but it incresed , i donot know why execution increased
like
Task 2 63 9%
IDLE 214 30%
Task 2 74 10%
IDLE 715 102%
Task 2 85 12%
IDLE 715 102%
Task 2 568 81%

Which clock is used for the stats?