This graph shows the amount of onion-service traffic from version 2 and version 3 onion services relayed by rendezvous points. This number is extrapolated from aggregated statistics on onion-service traffic reported by single relays acting as rendezvous points for version 2 and 3 onion services, if at least 1% of relays reported these statistics. For more details on the extrapolation algorithm, see this blog post and this technical report.