Question: Among the suppliers in the European region, what percentage have a below-average account balance?
SQL: SELECT CAST(SUM(IIF(T3.s_acctbal < ( SELECT AVG(supplier.s_acctbal) FROM supplier ), 1, 0)) AS REAL) * 100 / COUNT(T1.n_nationkey) FROM nation AS T1 INNER JOIN region AS T2 ON T1.n_regionkey = T2.r_regionkey INNER JOIN supplier AS T3 ON T1.n_nationkey = T3.s_nationkey WHERE T2.r_name = 'EUROPE'