and country of origin- needs something like 'their'
-immigrants plummeted to around 4 millions - is this plummeting? 25% less over a decade- it's a decline, but not plummeting to me
a peak to well under 9 millions.- preposition
the original country of people- rephrase
In 1882, immigrants came from Germany, Ireland and Britain nearly a half of all , whereas, Russian, Italian, Australian and Hungarian immigrated to the United States in 1907 at two thirds overall.- rewrite the sentence
the considerably more number - rewrite