Write SQL query to solve given problem: How much more total box office gross did the Walt Disney Company have in revenue in 1998 than in 1997?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT SUM(CASE WHEN `Year` = 1998 THEN Total ELSE 0 END) - SUM(CASE WHEN `Year` = 1997 THEN Total ELSE 0 END) FROM revenue