-- Database schema
| country : origin [ INTEGER ] primary_key , country [ TEXT ] | price : ID [ INTEGER ] primary_key , price [ REAL ] | data : ID [ INTEGER ] primary_key data.ID = price.ID , mpg [ REAL ] , cylinders [ INTEGER ] , displacement [ REAL ] , horsepower [ INTEGER ] , weight [ INTEGER ] , acceleration [ REAL ] , model [ INTEGER ] , car_name [ TEXT ] | production : ID [ INTEGER ] production.ID = data.ID , model_year [ INTEGER ] , country [ INTEGER ] production.country = country.origin |
-- -- How many cars were released in the USA in 1981?

SELECT COUNT(*) FROM production AS T1 INNER JOIN country AS T2 ON T1.country = T2.origin WHERE T2.country = 'USA' AND T1.model_year = 1981;