Which years did Michigan state university come in third place?
CREATE TABLE "table1_2331549_1" (
  "year" real,
  "host_city" text,
  "host_school" text,
  "champion" text,
  "second_place" text,
  "third_place" text
);
SELECT "year" FROM "table1_2331549_1" WHERE "third_place"='Michigan State University';