In 2009, 80.6% of Fort Worth (city) commuters drive to work alone. The 2009 modal share for Fort Worth (city) commuters are 11.7% for carpooling, 1.5% for transit, 1.2% for walking, and .1% for cycling. In 2015, the American Community Survey estimated modal shares for Fort Worth (city) commuters of 82% for driving alone, 12% for carpooling, .8% for riding transit, 1.8% for walking, and .3% for cycling. The city of Fort Worth has a lower than average percentage of households without a car. In 2015, 6.1 percent of Fort Worth households lacked a car, and decreased to 4.8 percent in 2016. The national average was 8.7 percent in 2016. Fort Worth averaged 1.83 cars per household in 2016, compared to a national average of 1.8.
Question: How many percentage points did the most common form of transportation increase by between 2009 and 2015?
Answer: 1.4