Japan should more than double the consumption tax rate to as high as 26 percent to ensure its fiscal sustainability, the Organization for Economic Cooperation and Development said Monday.In its biennial report, the OECD said Japan faces the intertwined challenges of a rapidly graying population and large government debt, which require a "comprehensive fiscal consolidation plan, including specific spending cuts and tax increases."Japan's fiscal health has remained the worst among advanced economies, with public debt equivalent to 236 percent of gross domestic product last year, according to …READ FULL ARTICLE