Where have all the people gone?

The CIA has recently updated its handbook, including the pages referring to the Cook Islands. (https://www.cia.gov/library/publications/the-world-factbook/geos/cw.html)
It contains some interesting information. It’s not all correct and some of it is out of date but it still makes for a good read.
Take the population figures.
The CIA estimated there were 12,271 people in the Cook Islands in July 2008.
The Cook Islands Statistics Department has a selection of population tables on its website (www.stats.gov.ck). These give a 2007 (provisional) population of 21,100. Huh? Well, OK they say there is a resident population of 12,500 but they don’t really explain what they mean by this – except that it’s people who are resident in the Cook Islands, Duh!
Cook Islanders obviously and permanent residents. But does it include workers and their families here on short term contracts? The thing is, the non-residents are classed as visitors and most people would assume this means tourists but 8600 is an awful lot of tourists to have on Rarotonga (and to a lesser extent Aitutaki and other southern group islands) at one time, especially with the number of rooms available in hotels and motels being in the region of 1000 with an occupancy rate of about 80% in June 2006 (the most recent figures available on the website).
I wonder where the CIA got the 12,271 figure. It’s understandable that it is less than the Stats Department number because there is a net outflow every year as people head for the bright lights of Auckland and Sydney, but after juggling the numbers the CIA has 229 fewer bodies than Stats.
Does the CIA know something about us that we don’t know?
And does anybody know how many people actually live here?
The Cook Islands International Sevens tournament took place on Friday and Saturday. It was very successful, great fun. A video is on the way…