'Ministers who teach the Bible' appear to include not only baptised publishers but also un-baptised publishers,
JW's have been counting it that way all time long since the time they have started to maintain stats. The ration of JWs to population has been counted the same way every year: Population/Peak Publishers.
In JW land, ministers who teach the bible (Publishers) refers to all JW's who go for field service and turn in reports. All unbaptized publishers are required to regularly go for preaching, conduct return visits and bible studies and turn in their monthly field service reports. So technically, unbaptized publishers too fall into the category of "Minsters who teach the Bible" and hence they include it in their numbers.