As seen that the numbers of the statistic are higher than the publisher numbers, both the official JW stats and the newsweek stats could be valid. They just counted different things.
In New Zealand, the official Census numbers for JWs are always been higher than the number of official publishers because even newborns are counted as JWs on the census and, of course, even inactive ones could specify their denomination as JW. Of interest, the latest New Zealand census recorded a decrease of almost three thousand among the JWs taking the number down from well over 19,000 to about 17,000. The official number of publishers has hovered around 13,000. It's all part of an inexorable decrease noted in most other western countries.