http://nfap.com/wp-content/uploads/2016/03/Immigrants-and-Billion-Dollar-Startups.NFAP-Policy-Brief.March-2016.pdf
WSJ summary
http://blogs.wsj.com/digits/2016/03/17/study-immigrants-founded-51-of-u-s-billion-dollar-startups
"“A new non-partisan study on entrepreneurship gives some credence to the tech industry’s stance that American innovation benefits from robust immigration.
The study from the
National Foundation for American Policy, a non-partisan think tank based in
Arlington, Va., shows that immigrants started more than half of the current
crop of U.S.-based startups valued at $1 billion or more.
These 44 companies,
the study says, are collectively valued at $168 billion and create an average
of roughly 760 jobs per company in the U.S. The study also estimates that
immigrants make up over 70% of key management or product development positions
at these companies.”