Year % 1997 14.182534471437952 1998 16.76145868183339 1999 14.66284987277353 2000 15.581098339719022 2001 14.98844503136348 2002 16.846652267818566 2003 19.536903039073792 2004 19.872537659327907 2005 20.88039386041123 2006 21.02402745995423 2007 21.859799713876964 2008 23.123037396517276 2009 23.936471922858765 2010 24.29771213437591 2011 24.374288964732646 2012 26.080773606370876 2013 27.516778523489926 2014 29.19831223628692 2015 29.78465271458903 2016 30.84269662921348 2017 31.029496818970504 2018 33.007812500000014 2019 33.547306726207104 2020 34.76754259312737 2021 36.041787579802666 2022 36.864896073903 2023 36.80908276068121