Canada has had the greatest decline over this time, and NZ the least.
	Inter-country comparison of trends in smoking prevalence - the % of adults who smoke
	Method
	Selection of the lowest smoking prevalence OECD countries/states
	Inter-country comparison by average rates of annual decrease, to eliminate inter-country differences in survey methods.
	3-year centred averages for start and end points to reduce survey sampling error
	Maximum observation period  (1990-2  to 2002-4) to eliminate the effect of one-off events