Question: In which city has the greatest population, what is its percentage to its country population?
SQL: SELECT T3.Name, CAST(T3.Population AS REAL) * 100 / T1.Population FROM country AS T1 INNER JOIN province AS T2 ON T1.Code = T2.Country INNER JOIN city AS T3 ON T3.Country = T2.Country ORDER BY T3.Population DESC LIMIT 1