How many christmas albums were released in 2004?
album refers to releaseType; groupYear = 2004; tag = 'christmas';
SELECT COUNT(T1.id) FROM torrents AS T1 INNER JOIN tags AS T2 ON T1.id = T2.id WHERE T2.tag = 'christmas' AND T1.groupYear = 2004 AND T1.releaseType LIKE 'album'