I don't know ... that seems like a heck of a lot of people partaking by mistake. There must be some kind of brain-virus epidemic among JWs for there to be so many of them making that particular mistake. I think if we check the records it will be seen that the number of partakers stopped decreasing soon after Watchtower had new light reversing the teaching that the heavenly calling ended in 1935.
The increase in partakers is evidence that JW anointings are not coming from Jehovah's spirit but are basically based on individual bravery and the permission implicit in Watchtower doctrine. When the org. dropped the 1935 cut-off for new anointeds, they implicitly gave permission for more JWs to claim to be anointed and thus we see an increasing number of anointed. This also begs the question - for those who believe in god and anointing - how many truly anointed JWs have rejected their anointing because they were dissuaded from accepting that calling by Watchtower teachings? I seem to remember Jesus saying something about the wicked religious leaders shutting up the kingdom of heaven, preventing others from going in...