They are low. As with the previous charts I shared in this thread, the data in these charts represent primarily the main sets in english as stated.
CGC has graded the equivalent of 36% of PSA’s total within this data (for the same given sets).
BGS has graded the equivalent of 3.1% of PSA’s total within this data (for the same given sets).
BGS has graded the equivalent of 8.7% of CGC’s total within this data (for the same given sets).
As for how often they update, I have no idea. Their pop is so small it’s not something I use often.