Write SQL query to solve given problem: What is the ratio for subscriber to customer given that the starting and the ending stations is 2nd at South Park?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(SUM(IIF(subscription_type = 'Subscriber', 1, 0)) AS REAL) / SUM(IIF(subscription_type = 'Customer', 1, 0)) FROM trip WHERE start_station_name = '2nd at South Park' AND end_station_name = '2nd at South Park'