Year % 1990 15.0724637681159 1991 14.7286821705426 1992 14.2666666666667 1993 13.8967136150235 1994 13.4550371872887 1995 13.0761523046092 1996 12.6797880393641 1997 12.3054331864905 1998 11.9839584807738 1999 11.6784037558685 2000 11.3875438303557 2001 11.1305872042068 2002 10.9262413205817 2003 10.7757065544197 2004 10.655090765588 2005 10.5579399141631 2006 10.4563716905326 2007 10.3745541022592 2008 10.3045829775121 2009 10.2452710652548 2010 10.1662952168695 2011 10.0599760095962 2012 9.96279761904762 2013 9.87406587323554 2014 9.79052529809861 2015 9.72180315008147 2016 9.69949250156811 2017 9.68577907353418 2018 9.67775093796577 2019 9.68090859924283 2020 9.67925063866023 2021 9.68864468864469 2022 9.70561998215879