What is the ERP for the Rockhampton region?
CREATE TABLE "main_transmitters" (
  "region_served" text,
  "city" text,
  "channels_analog_digital" text,
  "first_air_date" text,
  "erp_analog_digital" text,
  "haat_analog_digital_1" text,
  "transmitter_location" text
);
SELECT "erp_analog_digital" FROM "main_transmitters" WHERE "region_served"='rockhampton';