Among all the incidents with no arrest made, what is the percentage of them having a generic description of "BATTERY" in the IUCR classification?
incident with no arrest made refers to arrest = 'FALSE'; general description refers to primary_description; "BATTERY" is the primary_description; percentage = Divide (Count(iucr_no where primary_description = 'BATTERY'), Count(iucr_no)) * 100
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'