Write SQL query to solve given problem: What were the difference of the CHS team's winning rate between 1946 and 1947 in the post-season series games? Please provide your answer in percentages.. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(SUM(CASE WHEN year = 1947 AND tmIDWinner = 'CHS' THEN 1 ELSE 0 END) AS REAL) * 100 / SUM(CASE WHEN year = 1947 THEN 1 ELSE 0 END) - CAST(SUM(CASE WHEN year = 1946 AND tmIDWinner = 'CHS' THEN 1 ELSE 0 END) AS REAL) * 100 / SUM(CASE WHEN year = 1946 THEN 1 ELSE 0 END) FROM series_post