Firebird - Listar tabelas com mais colunas

SELECT
   TABS.RDB$RELATION_NAME AS NOME_TABELA ,
   ( SELECT COUNT(1) FROM RDB$RELATION_FIELDS CAMPS WHERE CAMPS.RDB$RELATION_NAME = TABS.RDB$RELATION_NAME ) AS NUM_CAMPOS
FROM RDB$RELATIONS TABS
WHERE
   TABS.RDB$SYSTEM_FLAG=0
ORDER BY
   2 DESC, 1