user: Question: What is Country of Origin, when Year of Intro is 1977?
Columns: ['Name/ designation', 'Year of intro', 'Country of origin', 'Primary cartridge', 'Type']
Types: ['text', 'real', 'text', 'text', 'text']
Sample row: ['M1 Bazooka', 1942.0, 'United States', '60mm', 'Recoilless']
SQL:

assistant: SELECT "Country of origin" FROM "Table" WHERE "Year of intro" = 1977.0;