galera TRX per seconds

SELECT ROUND(SUM(trx)/60) AS transactions_per_second FROM
  (SELECT VARIABLE_VALUE * -1 AS trx
        FROM information_schema.GLOBAL_STATUS
        WHERE VARIABLE_NAME = 'wsrep_last_committed'
    UNION ALL SELECT sleep(60) AS trx
    UNION ALL SELECT VARIABLE_VALUE AS trx
        FROM information_schema.GLOBAL_STATUS
        WHERE VARIABLE_NAME = 'wsrep_last_committed') AS COUNTED;