Note that the first huge drop was in the decade of the 1990's. That's when the WTS was "riding" the Wild Beast as a full-fledged NGO Member. One dasn't criticize the "Beast" when one is fornicating with it!
The next gigantic drop started precisely in 2000 when the WTS was first "exposed" for their hypocrisy of "riding" the Wild Beast and got DFd by the Beast when the Beast found out they had a history of condemning it as a tool of Satan. One dasn't keep reminding its members of an Organization like the UN lest the members get curious and do a little research and find the truth of the relationship the WTS has had with it.
I dare say that a search of the WT literature of the 1990s in the months of October and November would only find kindly articles about the Beast. That is when the WTS had to renew its annual Beast-riding ticket with the UN and prove to the UN it supported the goals of the UN.
A bigger bunch of religious assholes would be harder to find than the leaders of the WTS.
Farkel