What is the greatest number of bills sponsored in any year?
CREATE TABLE "legislation_sponsored_by_john_mc_cain" (
  "years_covered" text,
  "all_bills_sponsored" real,
  "all_amendments_sponsored" real,
  "all_bills_cosponsored" real,
  "all_amendments_cosponsored" real,
  "bills_originally_cosponsored" real,
  "amendments_originally_cosponsored" real
);
SELECT MAX("all_bills_sponsored") FROM "legislation_sponsored_by_john_mc_cain";