What is the percentage of the European countries among the given countries?
DIVIDE(COUNT(n_name where r_name = 'EUROPE'), COUNT(n_name)) as percentage;
SELECT CAST(SUM(IIF(T2.r_name = 'EUROPE', 1, 0)) AS REAL) * 100 / COUNT(T1.n_name) FROM nation AS T1 INNER JOIN region AS T2 ON T1.n_regionkey = T2.r_regionkey