Earnings in SA

Just stumbled across an interesting chart on a South Australian Website. It suggests that according to the ABS 2006 census, 18% of SA therapists make over $1000 per week as compared with 12% nationwide. What interests me is not just the figures (not sure that I'll move to Adelaide as a result), but the small numbers involved. I would have thought that more people would have listed themselves as being Massage Therapists on the census.