The 13 percent plunge against the dollar last month swelled Russia’s Reserve Fund by 919 billion rubles ($14 billion), almost six times what the Finance Ministry borrowed on local debt markets last year, official data show. The $85 billion fund, established in 2008 to help cushion against economic slowdowns, has given Putin flexibility to stay out of the debt market for a second year and avoid shouldering borrowing costs that have surged since his annexation of Crimea almost a year ago.