"This paper introduces two metrics for quantifying the financial stress posed by an ongoing plan's unfunded liability.... Key observations of these metric results across the MEPP universe from 2009 to 2013 include: ... [1] The vast majority of multiemployer pension plan participants are in plans for which the annualized cost of previously accrued benefits exceeds the costs of current benefit accruals and administrative expenses combined.... [2] [T]he highest stress levels are increasing over time. Only the lowest stress levels are improving appreciably."