CREATE TABLE rating (
	conversation_no numeric(4) NOT NULL,
	difficulty numeric(1),
	topicality numeric(1),
	naturalness numeric(1),
	echo_a numeric(1),
	echo_b numeric(1),
	static_a numeric(1),
	static_b numeric(1),
	background_a numeric(1),
	background_b numeric(1),
	remarks character(120)
);