OnionPerf vantage points are not comparable
OnionPerf results look to be comparable over time, but between vantage points there are systematic deltas between the results. The "all" plots show rises and falls where they actually don't exist, it's just that a particular vantage point was offline so the average of the two remaining moves noticeably.
We should work out how to have the aggregate value be resistant to the systematic delta due to the vantage point's location.