Proponents of mass immigration claim that it improves living standards by increasing productivity and ameliorating the aging of the population.
For example, modelling by McDonald and Temple in 2010 claimed that an annual migration intake between 160,000 and 220,000 is best for Australia and would increase GDP per capita by 12% more in 2053 versus zero net overseas migration.
However, the empirical evidence does not support the modelling’s conclusion. Australia massively increased its net migrant intake in the mid-2000s:

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