What percentage of patients with a proteinuria level within the normal range have a uric acid level below the normal range?
proteinuria level within the normal range refers to `U-PRO` > 0 AND `U-PRO` < 30; uric acid level below the normal range refers to UA < = 6.5; calculation = MULTIPLY(DIVIDE(UA < = 6.5, `U-PRO` > 0 AND `U-PRO` < 30)，100)
SELECT CAST(SUM(CASE WHEN UA <= 6.5 THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(ID) FROM Laboratory WHERE `U-PRO` > 0 AND `U-PRO` < 30