Write SQL query to solve given problem: What is the percentage of 5 star ratings River City brand root beer get?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(COUNT(CASE WHEN T2.StarRating = 5 THEN 1 ELSE NULL END) AS REAL) * 100 / COUNT(T2.StarRating) FROM rootbeerbrand AS T1 INNER JOIN rootbeerreview AS T2 ON T1.BrandID = T2.BrandID WHERE T1.BrandName = 'River City'