CREATE TABLE table_39490 ("Volume:Issue" TEXT, "Issue Date ( s ) " TEXT, "Weeks on Top" FLOAT, "Song" TEXT, "Artist" TEXT)

When was the song by Andy Gibb issued?
SELECT "Issue Date(s)" FROM table_39490 WHERE "Artist" = 'andy gibb'
SELECT "Issue Date(s)" FROM "table_39490" WHERE "Artist" = 'andy gibb'