Slammed by a 70 percent increase in illegal pipeline taps in one year, Mexico's state oil company announced Tuesday that it will no longer ship finished, usable gasoline or diesel through its network of ducts. Analysts said it was a striking admission of Mexico's inability to stop the fuel thefts, in which thieves drill into pipelines operated by Petroleos Mexicanos more than 10 times each day, on average. "This is a big admission of the vulnerab…