Year % 1997 13.132137030995105 1998 15.354874344103834 1999 14.335198507860373 2000 15.157425466703813 2001 14.374830485489552 2002 16.118165327805123 2003 18.46901579586876 2004 19.009468317552795 2005 20.20863658418243 2006 20.34060925881506 2007 21.10685194058457 2008 22.161128376763095 2009 22.701286326822295 2010 23.00606060606062 2011 23.034647550776587 2012 24.485891917742705 2013 25.751282677742484 2014 27.46077032810271 2015 27.90110998990919 2016 28.801135020099316 2017 29.74051896207585 2018 31.196083003031024 2019 31.669776119402993 2020 32.75779376498802 2021 34.40886106429087 2022 35.73393348337083 2023 35.699588477366255