better-than-market returns can also cause portfolio managers to take on more risk. The International Monetary Fund reported in April 2012 that developed countries may be underestimating the impact of longevity on their public and private pension calculations. The IMF estimated that if individuals live three years longer than expected, the incremental costs could approach 50% of 2010 GDP in advanced economies and 25% in emerging economies. In the United States, this would represent a 9% increase in pension obligations. The IMF recommendations included raising the retirement age commensurate with life expectancy. United States The Pension Benefit Guaranty Corporation’s (PBGC) financial future is uncertain because of long-term challenges related to its funding and governance structure. PBGC's liabilities exceeded its assets by about $51 billion as of the end of fiscal year 2018—an increase of about $16 billion from the end of fiscal year 2013. In addition, PBGC estimated that its exposure to potential additional future losses for underfunded plans in both the single and multiemployer programs was nearly $185 billion, of which the single-employer program accounts for $175 billion of this amount. PBGC projected that there is more than a 90 percent likelihood that the multiemployer program will be insolvent by the year 2025 and a 99 percent likelihood by 2026. U.S. Social Security program The number of U.S. workers per retiree was 5.1 in 1960; this declined to 3.0 in 2009 and is projected to decline to 2.1 by 2030. The number of Social Security program recipients is expected to increase from 44 million in 2010 to 73 million in 2030. The present value of unfunded obligations under Social Security as of August 2010 was approximately $5.4 trillion. In other words, this amount would have to be set aside today such that the principal and interest would cover the shortfall over the next 75 years. The Social Security Administration projects that an increase in payroll taxes equivalent to 1.9% of the payroll tax base or 0.7% of GDP would be necessary to put the Social Security program in fiscal balance for the next 75 years. Over an infinite time horizon, these shortfalls average 3.4% of the payroll tax base and 1.2% of GDP. According to official government projections, the Social Security is facing a $13.2 trillion unfunded liability over the next 75 years. U.S. State-level issues Since 2001, the financial health of state and local retirement systems have struggled to