user: Question: How many cabins were built in the time between 1967-1987?
Columns: ['Model', 'Seats', 'Period', 'Built', 'Country']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Fokker F28 Fellowship', '65-79', '1967-1987', 241.0, 'Netherlands']
SQL:

assistant: SELECT SUM("Built") FROM "Table" WHERE "Period" = '1967-1987';