Rederive and publish "fraction of network traffic that is onion service related"

What fraction of overall Tor network traffic has to do with onion services?

Back in 2015, we calculated that it was around 3% of Tor client traffic (or, if most onion service traffic uses 6-hop circuits, about 6% of traffic from a relay's perspective):
https://blog.torproject.org/some-statistics-about-onions/
https://research.torproject.org/techreports/hidden-service-stats-2015-04-28.pdf

Karsten made a new set of graphs and conclusions for me for the 2017 onion services talk at Defcon: see slides 29-31 of
https://freehaven.net/~arma/slides-dc17.pdf

In those graphs, we see that "percent of Tor client traffic" grow from 3% in 2015 up to a peak of almost 8% in mid 2016 and then fall back to 3% for the first half of 2017.

And during those times the corresponding estimate of total fraction of what relays carry started at maybe 5%, peaked at almost 12% in mid 2016, and went back to around 5% for 2017.

What is our number after 2017? I don't think anybody has computed it. The best instructions that I have found come from Karsten and @amj703 in this tor-dev post:
https://lists.torproject.org/pipermail/tor-dev/2015-February/008249.html

We should re-learn how to compute it, and then find what this year's number is, and then think about ways to streamline getting more consistent / frequent data points.