Though in 2007 some suggested that a subsidy shift would help to level the playing field and support growing energy sectors, namely solar power, wind power, and bio-fuels.,[23] by 2017 those sources combined had yet to provide 10% of U.S. electricity, and intermittency forced utilities to remain reliant on oil, natural gas, and coal to meet baseload demand. Many of the "subsidies" available to the oil and gas industries are general business opportunity credits, available to all US businesses (particularly, the foreign tax credit mentioned above). The value of industry-specific (oil, gas, and coal) subsidies in 2006 was estimated by the Texas State Comptroller to be $6.25 billion - about 60% of the amount calculated by the Environmental Law Institute.[24] The balance of federal subsidies, which the comptroller valued at $7.4 billion, came from shared credits and deductions, and oil defense (spending on the Strategic Petroleum Reserve, energy infrastructure security, etc.).