Year % 1997 16.61476868327403 1998 16.770462633451967 1999 17.974918718067805 2000 19.3723188078573 2001 19.176262178919405 2002 19.133489461358305 2003 20.690459528808024 2004 21.705243268776563 2005 22.144784172661872 2006 22.994173016584487 2007 24.524076147816366 2008 24.82094897045659 2009 25.396470851016307 2010 25.262452535179804 2011 25.97228430934287 2012 27.303220035778175 2013 29.759251003120813 2014 29.899665551839465 2015 29.692376281765497 2016 29.723090665475667 2017 30.792883812870635 2018 31.524604569420028 2019 32.9453107840984 2020 33.76509330406147 2021 34.48275862068966 2022 34.127893651157464 2023 34.53253895508706