How many cosponsors have a Date introduced of may 22, 2008?
CREATE TABLE "legislative_activity" (
  "congress" text,
  "bill_number_s" text,
  "date_introduced" text,
  "sponsor_s" text,
  "num_of_cosponsors" real
);
SELECT COUNT("num_of_cosponsors") FROM "legislative_activity" WHERE "date_introduced"='may 22, 2008';