Among the releases that were released in 2000, how many of them were released as an album and tagged "pop"?
groupYear = 2000; album refers to releaseType;
SELECT COUNT(T1.groupName) FROM torrents AS T1 INNER JOIN tags AS T2 ON T1.id = T2.id WHERE T2.tag = 'pop' AND T1.releaseType = 'album' AND T1.groupYear = 2000