STOCKTON — More than two million Pacific Gas and Electric Company customers, which includes more than 80,400 San Joaquin County residential customers, are on track to qualify for gas bill credits through the utility’s Winter Gas Savings program, based on December usage reductions. If sustained, that number would exceed the total achieved in last year’s program – with additional customers still able to earn bill credits through January if they step up their energy savings. The program provides eligible residential and business customers with an automatic gas bill credit of up to 20 percent for reducing natural gas usage during peak months. (Reductions are based on usage over the three previous winters, adjusted for weather.) Customers who lower usage during December 2012 and January 2013 by 10 percent or more will receive a 20 percent credit.