steve2 My hunch is that numbers attending conventions in New Zealand have been slowly declining for a few years now - but I do not have hard evidence to back up my hunch
Your hunch is correct, the chch convention is always a good one to gauge numbers over the years. There is only the one convention for the whole south island, no boundary changes to distort attendance figures. During the 90s attendance was always closer to 4000 with always 60+ being baptized. This year, 3 of the 6 sessions had under 3000 attending.