Custom Calc: % of Time a certain data point is above or > another

Requested by Jim Arazini at JH - $124k

I wanted to see if there is any word of building out the rolling returns function on ycharts. I think it is one of the more useful tools in the fundamental chart, but I would love an option if it could calculate % of time one strategy is higher than another as well as the average out/underperformance. I would love to speak further if I need to clarify anything.

Inspiration for this idea here: https://link.ycharts.com/p69