Year % 1997 11.692171061620442 1998 13.070822231860717 1999 13.520105471324989 2000 13.904439526103372 2001 14.090700870361886 2002 15.197445911598784 2003 15.179207215760742 2004 15.89700056593096 2005 16.47454501071361 2006 16.969664226478294 2007 17.86920230152084 2008 18.442754632108816 2009 19.025086573792592 2010 19.15703781512605 2011 19.82776672599728 2012 20.755204297742647 2013 21.777447441070294 2014 22.188296516567547 2015 22.84929915793364 2016 23.091367424632168 2017 23.59033667437677 2018 24.09787827164318 2019 24.636603686517805 2020 25.5804311774461 2021 26.12846321469337 2022 26.467619401795677 2023 26.73574852063084