What was the percentage in 2006 that had less than 9% in 1970?
CREATE TABLE "pct_foreign_born_by_borough_1970_2006" (
  "borough" text,
  "1970" real,
  "1980" real,
  "1990" real,
  "2000" real,
  "2006" real
);
SELECT AVG("2006") FROM "pct_foreign_born_by_borough_1970_2006" WHERE "1970"<9;