Year	Percent
1991	34.683
1992	34.761
1993	34.949
1994	35.235
1995	35.306
1996	35.355
1997	35.732
1998	36.092
1999	36.316
2000	36.858
2001	37.132
2002	37.271
2003	37.543
2004	37.86
2005	37.933
2006	38.182
2007	38.324
2008	38.214
2009	37.892
2010	37.973
2011	38.169
2012	38.103
2013	38.244
2014	38.472
2015	38.644
2016	38.828
2017	38.94
2018	39.082
2019	39.28
2020	39.512
2021	39.765
2022	40.016