ülkeyi terk etmeye başladı massive exodus sobre cinco millones Puerto Ricans Leave in Record Numbers for Mainland U.S. Pew Research Center significant Pew Research migration of Puerto Ricans significant rise in Puerto Rican migration to the mainland relocating According to the Pew Research Center according to the Pew Research Center found migration has begun anew Pew Research Center census data show According to the Pew Research Center Pew Research Center experiencing Pew found waves of emigration