The statutory retirement age—when citizens can claim state pensions—dates back to the Roman Empire in 13 BC, but the first official age was set by Otto von Bismarck in Germany in 1889 at 70, later reduced to 65. Britain and the US adopted their own systems in 1908 and 1935, and by the mid-20th century, nearly all countries had one. Modern policymakers weigh factors like life expectancy, fiscal costs, and unpaid parental care, leading to debates about raising ages and equalizing them between men and women, who generally live longer. Reforms typically phase in increases slowly with "grandfathering" (as seen with EU civil servants in 2014), while decreases are often rapid. Currently, the OECD average in 2014 was 65 for men and 63.5 for women, but the trend is upward—the US requires 67 for those born after 1960, Denmark targets 70 by 2040, and many EU states aim for 67 by 2030.