How to raise migraation Index?

I see from reading game documentation migration index is derived from welfare index, employment index, and salary levels.

My country is small -- only 15 + million pop.

so what are good index level for welfare , employment and salaries, so I can attract migrants?

200 welfare index for workers in corporations is a good start. (220 better)

Employment should be at least above 85 employment index. (92.5 for flexibility / 95 better)

Salary should be at least 200 for state corporations.