This is irrelevant because of 2 factors:

1. Past policies don't dictate current policies. And current policies are wildly different from policies of 5 years ago, which are again different of policies of 20 years ago and even before that.

2. Amount of immigrants doesn't say anything about standard of living. And we all know immigration (and even illegal immigration) was promoted by all parties because this meant cheaper labor costs. And often also, exploitable labor.

And finaly... it's not a surprised that the third largest country in the world, who was considered an immigrant nations for well over 2 centuries has the most immigrants?

Now look at the same metric per capita - USA immediately loses its 1st place.