Oh... forgot to mention.
In the industrialized nations, there is a huge die-off coming regarding the Baby Boomer generation. In addition, Christian birth rates are down and not keeping pace with what is needed to maintain population levels. So these countries have to accept immigration to keep the population even keeled. A lot of these immigrants are not Christian.
Within 10 to 20 years the Baby Boomers are gonna start dying off. So if a congregation is made up of mostly older people, sooner or later they are bound to shuck this mortal coil and their numbers will go down in addition to those who 'wake up'.
I guess Botchtower doesn't keep records on who dies off.