When looking at the irc users graph on Zabbix.org, I noticed the graph period was stated as 6y 12m 1d. Since 12m is actually a year, one would expect it to show 7y 1d.

https://www.zabbix.org/zabbix/history.php?action=showgraph&itemid=623&sid=6672e95b2b36bef3