user: Question: What year was number 7 built?
Columns: ['Class', 'Operator', 'No. Built', 'Year Built', 'Cars per Set', 'Unit nos.']
Types: ['text', 'text', 'real', 'text', 'real', 'text']
Sample row: ['Class 170/1', 'CrossCountry', 17.0, '1998–1999', 3.0, '170 101 - 170 110']
SQL:

assistant: SELECT "Year Built" FROM "Table" WHERE "No. Built" = 7.0;