user: Question: Name the sum of inversions for opened of April 20, 2002
Columns: ['Name', 'Park', 'Country', 'Inversions', 'Opened', 'Status']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Bizarro Formerly Medusa', 'Six Flags Great Adventure', 'United States', 7.0, 'April 2, 1999', 'Operating']
SQL:

assistant: SELECT SUM("Inversions") FROM "Table" WHERE "Opened" = 'April 20, 2002';