Xcode debug gauge Watch cpu over 100%

The CPU gauge in Xcode debugger displays "Percentage Used" in a gauge with a scale from 0 to 200. When debugging my watch app on an Apple Watch Series 2, it happily goes to 180% without discernable performance degradation.

I can only surmise that it's something to do with the dual core CPU - but what is it really measuring, and how can it be used?