San Antonio, Texas — The American Automobile Association said Tuesday that the city’s fleet of about 5.7 million vehicles is up by more than 5 million since January, the most since the auto industry began reporting data on the data in 1992.

The increase was driven by the expansion of the city and county’s electric vehicle charging network and the addition of electric vehicle owners to the city fleet, according to the association.

The association said San Antonio now has more than 4 million electric vehicles.

More than half of San Antonio’s fleet now has a charger, according the association, which said the number of electric vehicles in San Antonio has more recently jumped from a low of about 4 million in December 2016 to about 8.7 milion in September 2017.

The association said the increased electric vehicle ownership is “part of a broader trend” in the city, where the average owner of a new car is 40 years old.

That is up from a lower average of 34 years old in 2011.

The city added about 1.4 million new vehicles last year, the association said, with an average price tag of $1,832.

The average cost of a second-generation Toyota Prius was $4,931, according data from the National Association of Manufacturers.

The San Antonio region has the most vehicles on the road, with about 2.7 mpg per person, up from 1.7 in 2017, according a report from the Association of Texas Automobile Dealers.

The region has about 787,000 residents.

San Antonio has the nation’s second-highest share of electric cars in terms of number, followed by Austin, Texas, with 2.9 percent.

The top three cities are Seattle, with 1.9; San Jose, California, with 0.8; and Phoenix, Arizona, with -0.4 percent.