user: Question: How many targets are there with an approval date of 1997?
Columns: ['Antibody', 'Brand name', 'Approval date', 'Type', 'Target', 'Approved treatment(s)']
Types: ['text', 'text', 'real', 'text', 'text', 'text']
Sample row: ['Alemtuzumab', 'Campath', 2001.0, 'humanized', 'CD52', 'Chronic lymphocytic leukemia']
SQL:

assistant: SELECT COUNT("Target") FROM "Table" WHERE "Approval date" = 1997.0;