Onion services are services that are only accessible via the Tor network.
This graph shows the fraction of relays that report statistics on onion service usage. If at least 1% of relays report a statistic, it gets extrapolated towards a network total, where higher fractions are produce more accurate results. For more details on the extrapolation algorithm, see this blog post and this technical report.
This material is supported in part by the National Science Foundation under Grant No. CNS-0959138. Any opinions, finding, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. "Tor" and the "Onion Logo" are registered trademarks of The Tor Project, Inc.. Data on this site is freely available under a CC0 no copyright declaration: To the extent possible under law, the Tor Project has waived all copyright and related or neighboring rights in the data. Graphs are licensed under a Creative Commons Attribution 3.0 United States License.