Question: Among all the incidents with no arrest made, what is the percentage of them having a generic description of "BATTERY" in the IUCR classification?
SQL: SELECT CAST(SUM(CASE WHEN T1.primary_description = 'BATTERY' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(*)FROM IUCR AS T1 INNER JOIN Crime AS T2 ON T1.iucr_no = T2.iucr_no WHERE T2.arrest = 'FALSE'