What proportion of suppliers are from Asia?
Asia refers to r_name = 'ASIA'; proportion = divide(count(s_name where r_name = 'ASIA'), count(s_name)) * 100%
SELECT CAST(SUM(IIF(T1.r_name = 'ASIA', 1, 0)) AS REAL) * 100 / COUNT(T1.r_regionkey) FROM region AS T1 INNER JOIN nation AS T2 ON T1.r_regionkey = T2.n_regionkey INNER JOIN supplier AS T3 ON T2.n_nationkey = T3.s_nationkey