What is the maximum t20 on green lane?
CREATE TABLE "ground_history" (
  "name_of_ground" text,
  "location" text,
  "year" text,
  "fc_matches" real,
  "la_matches" real,
  "t20_matches" real,
  "total" real
);
SELECT MAX("t20_matches") FROM "ground_history" WHERE "name_of_ground"='Green Lane';