The percentage of baptisms at summer conventions is not the annual growth measure but does give a feel for more than half, perhaps two thirds(?) of the annual baptisms in a large area. I predict they will stop having baptisms at circuit assemblies because it is discouraging to have so few candidates............
The Atlanta figures are telling because we have the ages of the dunked-- and as teens it is likely that they are doing it primarily for their family and family tradition not for personal conscientious or 'spiritual' reasons. If this is representative of most baptisms today (young born-ins) it shows that the door to door preaching work has become a FAILURE! An enormous effort for few rewards in terms of getting outsiders on board the Watchtower ark. In other words it's much easier to believe the JW drivel if you were born into it.
However it is encouraging to know that past statistics show that whatever the reasons for getting baptised, JWs have a very high churn rate and most of these newbies will leave the organisation sooner or later.