The proportion of Asian workers has increased over time in trade sectors. For some sectors this has been gradual incline over the past 20 years while for sectors the rise has been more sudden in the past 6 years.
Methodology
Trade workers are defined from IRD tax records. To be considered an employee in a year they must earn at least the equivalent of 120 hours at the minimum wage in a month for three months in the year. We set no income threshold on self-employed workers.

