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: An American rapper '2Pac' released his first solo album in 1991, how many years have passed until his next album was released?
Evidence: 2Pac is an artist; album refers to releaseType; groupYear = 1991; SUBTRACT(groupYear = 1991, groupYear where releaseType = 'album' LIMIT 1 OFFSET 1);

SQL:
SELECT ( SELECT groupYear FROM torrents WHERE artist LIKE '2Pac' AND releaseType LIKE 'album' ORDER BY groupYear LIMIT 1, 1 ) - groupYear FROM torrents WHERE artist LIKE '2Pac' AND releaseType LIKE 'album' AND groupYear = 1991