Hi Bok,
On the page User by CPID Stats, the link JoinDate Rank of the line Combined (https://stats.free-dc.org/userdatecomb/12130 for me) always leads to the same test table Userdatecomb Stats for Users joining on Wed, 31 December 1969. This date seems to be the calendar origin and the table does not change when you modify the link to https://stats.free-dc.org/userdatecomb/10000 for instance.