why the percent number in the graph is not match as "timer %"

hello everyone, I am a very newer to use this tool. I did samplingby countingtimer event, and got the results and the histograms. However,I found they are not the same.The result summary shows that

intelppm.sys timer %(184) 81.93%

In the module histogram, the column of intelppm.sys has less than 70% length,

I atteched the screen capture.

Why?

Thanks everyone.