Pennsylvania had the 15th-highest state and local tax burden in the United States in 2012, according to the Tax Foundation. Residents paid a total of $83.7 billion in state and local taxes with a per capita average of $4,589 annually. Residents share 76% of the total tax burden. Many state politicians have tried to increase the share of taxes paid by out of state sources. Suggested revenue sources include taxing natural gas drilling as Pennsylvania is the only state without such a tax on gas drilling. Additional revenue prospects include trying to place tolls on interstate highways; specifically Interstate 80, which is used heavily by out of state commuters with high maintenance costs.