Year	Percent
1991	33.466
1992	42.855
1993	50.899
1994	57.551
1995	58.452
1996	56.585
1997	53.91
1998	50.969
1999	54.141
2000	57.783
2001	52.782
2002	55.29
2003	56.838
2004	56.49
2005	57.199
2006	57.363
2007	56.587
2008	52.001
2009	51.012
2010	49.106
2011	48.657
2012	47.267
2013	45.966
2014	44.804
2015	42.551
2016	41.82
2017	41.685
2018	40.594
2019	39.678
2020	38.613
2021	37.725
2022	36.803