user: Question: What is the total number of quantity when the introductory year was 1984?
Columns: ['Manufacturer', 'Model', 'Quantity', 'Introduced', 'Retired']
Types: ['text', 'text', 'real', 'real', 'real']
Sample row: ['Douglas', 'C-54 Skymaster', 6.0, 1947.0, 1966.0]
SQL:

assistant: SELECT SUM("Quantity") FROM "Table" WHERE "Introduced" = 1984.0;