Database: toxicology
Question: What proportion of single bonds are carcinogenic? Please provide your answer as a percentage with five decimal places.
SQL: SELECT ROUND(CAST(COUNT(CASE WHEN T2.label = '+' THEN T1.bond_id ELSE NULL END) AS REAL) * 100 / COUNT(T1.bond_id),5) FROM bond AS T1 INNER JOIN molecule AS T2 ON T1.molecule_id = T2.molecule_id WHERE T1.bond_type = '-'