With the automobile being the primary means of transportation for over 80 percent of its residents, San Diego is served by a network of freeways and highways. This includes Interstate 5, which runs south to Tijuana and north to Los Angeles; Interstate 8, which runs east to Imperial County and the Arizona Sun Corridor; Interstate 15, which runs northeast through the Inland Empire to Las Vegas and Salt Lake City; and Interstate 805, which splits from I-5 near the Mexican border and rejoins I-5 at Sorrento Valley.
What percentage of San Francisco's residents rely on their automobile as a primary source of transportation?