### Database Schema:
CREATE TABLE cites (
	cited_paper_id	TEXT	NOT NULL	PRIMARY KEY,
	citing_paper_id	TEXT	NOT NULL	PRIMARY KEY
);

CREATE TABLE content (
	paper_id	TEXT	NOT NULL	PRIMARY KEY,
	word_cited_id	TEXT	NOT NULL	PRIMARY KEY,
	foreign key (paper_id) references paper (paper_id)
);

CREATE TABLE paper (
	paper_id	TEXT	NOT NULL	PRIMARY KEY,
	class_label	TEXT	NOT NULL
);

### User's Query:
Calculate the percentage of words used in Agents class label.

### Extra Knowledge:
percentage = (divide(count(word_cited_id where class_label = 'Agents')), (count(word_cited_id)))*100;
SELECT CAST(COUNT(DISTINCT CASE WHEN T1.class_label = 'Agents' THEN T2.word_cited_id ELSE NULL END) AS REAL) * 100 / COUNT(DISTINCT T2.word_cited_id) FROM paper AS T1 INNER JOIN content AS T2 ON T1.paper_id = T2.paper_id