About 5 households
It all depends on the country you're asking about. Worldwide the average number of cars per household is probably less than one (<1) due to the staggering amount of people in Africa, India, and...
2-3 personas
well for two couples they must have two cars if they work separtly and if u live in the house they have 3 or more
In the USA it is either 120/208 or 120/240 depending on your local unility company