For years, Mexico has been a major fuel buyer from the United States. Then the government built a new refinery that cost $20 billion, which was planned to boost the country’s energy independence. It seems it has finally started to do just that—and fuel imports are on the decline. The Olmeca refinery, also called Dos Bocas, was the centerpiece of Mexico’s previous administration, with Andres Manuel Lopez Obrador at the helm and plans for an even greater role for state-owned Pemex in Mexico’s energy system. The project was…