The absolute number of foreign-born is far greater today - 40 million in 2010 and rising since 1990 by about a million a year, against a pre-1980 peak of 14m or so in 1910-30. But the proportion is still only edging back toward its previous peak - 13% in 2010 against around 14% in the half-century before WW1 (peaking at probably over 15% in 1914). See https://www.census.gov/newsroom/pdf/cspan_fb_slides.pdf

That's a rather broad question. Do you have a country or region of a country in mind?

Do you mean a number as in a percentage or flat population?