For which network was Chris Walby the color commentator after 1990?
CREATE TABLE "1990s" (
  "year" real,
  "network" text,
  "play_by_play" text,
  "colour_commentator_s" text,
  "pregame_host" text
);
SELECT "network" FROM "1990s" WHERE "year">1990 AND "colour_commentator_s"='chris walby';