http://onlinelibrary.wiley.com/doi/1...5.01037.x/full
Over time, all immigrant populations assimilate and approach natives. Meaning they compensate for falling birth rates
which are negative in every major western industrialized country.
I can provide some data on how economies over time are dependent on demographics for growth.
We need more young people to sustain our historic 3% growth, although this long-term average is likely to fall, simply due to demographics.
Conservative policies limiting refugees and immigration will hurt our long term prospects for economic growth of the USA.
This is a rather common thing pointed out by publications that deal with such data, such at the Economist.