Year % 1990 52.643989962321314 1991 53.02700985289786 1992 53.283152051555696 1993 54.12539162282073 1994 54.03911495257272 1995 54.271629621527424 1996 54.1797510040682 1997 54.26327854821241 1998 54.263234264244986 1999 54.23663698652848 2000 54.26485870030134 2001 54.19778703187878 2002 54.04212253872315 2003 54.03047403793668 2004 54.25256743754394 2005 54.27840427512122 2006 54.2783338497622 2007 54.303947183072154 2008 54.3605659264512 2009 54.39740777879312 2010 54.48615137008193 2011 54.64668477404656 2012 54.905546852068596 2013 55.15823665112897 2014 55.532975947089184 2015 55.834669315631736 2016 56.110267089152714 2017 56.40674086722923 2018 56.6443511109074 2019 56.91629586296461 2020 57.14874741989613 2021 57.34292073260172 2022 57.59028002002437