### Database Schema:
CREATE TABLE country (
	origin	INTEGER	NULL	PRIMARY KEY,
	country	TEXT	NULL
);

CREATE TABLE price (
	ID	INTEGER	NULL	PRIMARY KEY,
	price	REAL	NULL
);

CREATE TABLE production (
	ID	INTEGER	NULL	PRIMARY KEY,
	model_year	INTEGER	NULL	PRIMARY KEY,
	country	INTEGER	NULL,
	foreign key (ID) references data (ID),
	foreign key (country) references country (origin),
	foreign key (ID) references price (ID)
);

CREATE TABLE data (
	ID	INTEGER	NULL	PRIMARY KEY,
	mpg	REAL	NULL,
	cylinders	INTEGER	NULL,
	displacement	REAL	NULL,
	horsepower	INTEGER	NULL,
	weight	INTEGER	NULL,
	acceleration	REAL	NULL,
	model	INTEGER	NULL,
	car_name	TEXT	NULL,
	foreign key (ID) references price (ID)
);

### User's Query:
Among the car models introduced in the market in 1970, how many of them have the USA as their origin country?

### Extra Knowledge:
introduced in the market in 1970 refers to model_year = 1970; have the USA as origin country refers to country = 'USA'
SELECT COUNT(*) FROM production AS T1 INNER JOIN country AS T2 ON T1.country = T2.origin WHERE T1.model_year = 1970 AND T2.country = 'USA'