text: -- Your SQL goes here
  ALTER TABLE streamers ADD average_subscriber_ratio FLOAT NOT NULL DEFAULT 0;
  CREATE TABLE streamers_average_subscriber_distribution (
      streamer_id BIGINT NOT NULL REFERENCES streamers (id),
      month INT NOT NULL, 
      ratio FLOAT NOT NULL DEFAULT 0,
      PRIMARY KEY (streamer_id, month)
    );
  CREATE INDEX streamers_average_subscriber_distribution_streamer_id_idx ON streamers_average_subscriber_distribution(streamer_id);
  