-- Database schema
| torrents : groupName [ TEXT ] , totalSnatched [ INTEGER ] , artist [ TEXT ] , groupYear [ INTEGER ] , releaseType [ TEXT ] , groupId [ INTEGER ] , id [ INTEGER ] primary_key | tags : index [ INTEGER ] primary_key , id [ INTEGER ] , tag [ TEXT ] |
-- -- From 1979 to 1982, what was the percentage of united.states albums out of total albums were released?

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';