How many different percentages of immigrants in 2006 can there be for Morocco?
CREATE TABLE "by_country" (
  "country" text,
  "pct_of_all_immigrants_2008" text,
  "pct_of_all_immigrants_2007" text,
  "pct_of_all_immigrants_2006" text,
  "pct_of_all_immigrants_2005" text,
  "pct_of_all_immigrants_2004" text
);
SELECT COUNT("pct_of_all_immigrants_2006") FROM "by_country" WHERE "country"='Morocco';