What's the period of a rock album released in 1973?
CREATE TABLE "120_million_to_199_million_records" (
  "artist" text,
  "country_of_origin" text,
  "period_active" text,
  "release_year_of_first_charted_record" real,
  "genre" text,
  "claimed_sales" text
);
SELECT "period_active" FROM "120_million_to_199_million_records" WHERE "release_year_of_first_charted_record"=1973 AND "genre"='rock';