T'would appear that when counting delegate days at the Convention Centre they count the numbers of those attending the weekly church, The Meeting Place, which account for 125 delegates per week.
A little basic math: 125 x 52 = 6500 = 21.6% of the 30,000 delegates expected this year.
If you think of the 16,000 delegates they said they had in 2011 the Meeting Place would have accounted for 40.6% of these.
Below is a story about a conference that actually put the facility at capacity for a couple of day.
March 17, 2012 VICC hits capacity next week
I unfortunately deleted a couple of stories I had saved with regard to the conference Centre and its projected numbers for this year, 30,000 delegate days. In 2011 it had been projected that the conference centre would see the same 30,000 delegate days but only reached something in the effect of 16,000 or 2.5% overall capacity. In the event the centre does see 30,000 delegates this year it will only reach 5% capacity.
Will attempt to find the stories, as it is amusing to read the comments attached to them, and will post here when I do.