Counting the Whole Number of Persons -- Trump doesn't want to obey Constitution

[RocksInMyHead]

I don't see an easy source for that. The closest I've seen is that 85%-89% of the applications for ITINs in 2013-2014 came from people residing in the US.
FIGURE 1.18.2

There are some people here legally who aren't eligible for SSNs, so not all of those would necessarily be illegal. Most legal non-citizen residents can get a SSN though, so the vast majority of that number would be illegal immigrants.