Thanks, Roger! Finally, I found it! It was exonerator. Initially it was hosted (e.g. in 2012) at https://metrics.torproject.org/exonerator.html. Now it is (I don't know why) removed from metrics and moved to https://exonerator.torproject.org. However, it gives stat (all uptimes and downtimes) only for particular day, not for the whole history. Why it is not part of onionoo?
P.S. I would be very happy if you could reply also on this my old comment: https://blog.torproject.org/comment/reply/1297/232924
which is from old topic: https://blog.torproject.org/blog/tor-0299-released
More information about formatting options
Drupal Design and Maintenance by New Eon Media
Drupal Development by Chapter Three