Year	Percent
1991	46.841
1992	47.4
1993	49.022
1994	47.443
1995	45.981
1996	41.882
1997	40.721
1998	39.466
1999	36.122
2000	33.357
2001	32.854
2002	32.156
2003	31.188
2004	32.524
2005	32.117
2006	32.849
2007	35.489
2008	35.188
2009	30.867
2010	37.824
2011	38.421
2012	37.162
2013	36.122
2014	35.921
2015	36.056
2016	34.137
2017	33.787
2018	33.913
2019	33.955
2020	33.982
2021	33.984
2022	33.976