Year	Percent
1991	40.675
1992	40.537
1993	39.986
1994	39.413
1995	39.626
1996	39.155
1997	38.259
1998	38.262
1999	37.621
2000	38.003
2001	37.768
2002	37.829
2003	37.692
2004	37.956
2005	38.128
2006	38.753
2007	38.987
2008	39.098
2009	38.087
2010	38.322
2011	38.537
2012	38.102
2013	37.484
2014	36.806
2015	35.647
2016	35.056
2017	34.677
2018	34.516
2019	34.363
2020	34.23
2021	34.104
2022	33.98