Database schema:

CREATE TABLE tags (
	"index" INTEGER -- example: ['0', '1'],
	id INTEGER -- example: ['0', '2'],
	tag TEXT -- example: ['funk', '1970s'],
	PRIMARY KEY ("index"), 
	CONSTRAINT fk_tags_torrents FOREIGN KEY(id) REFERENCES torrents (id)
)


CREATE TABLE torrents (
	"groupName" TEXT -- example: ['spiderap / a corona jam', 'superappin&#39;'],
	"totalSnatched" INTEGER -- example: ['239', '156'],
	artist TEXT -- example: ['grandmaster flash & the furious five', 'ron hunt & ronnie g & the sm crew'],
	"groupYear" INTEGER -- example: ['1979', '1980'],
	"releaseType" TEXT -- example: ['single', 'album'],
	"groupId" INTEGER -- example: ['720949', '728752'],
	id INTEGER -- example: ['0', '1'],
	PRIMARY KEY (id)
)

Question: From 1979 to 1982, what was the percentage of united.states albums out of total albums were released?
Evidence: From 1979 to 1982 refers to groupYear between 1979 and 1982; United States refer to tag; albums refer to releaseType; DIVIDE(COUNT(releaseType = 'album' where tag = 'united.states' and groupYear between 1979 and 1982), COUNT(releaseType = 'album' where groupYear between 1979 and 1982)) as percentage;

SQL:
SELECT CAST(SUM(CASE WHEN T2.tag LIKE 'united.states' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T1.releaseType) FROM torrents AS T1 INNER JOIN tags AS T2 ON T1.id = T2.id WHERE T1.groupYear BETWEEN 1979 AND 1982 AND T1.releaseType LIKE 'album'