Year	Percent
1991	37.498
1992	33.904
1993	33.044
1994	31.798
1995	31.465
1996	30.162
1997	31.547
1998	33.456
1999	34.148
2000	33.318
2001	33.885
2002	35.129
2003	37.715
2004	38.406
2005	37.759
2006	37.409
2007	38.225
2008	38.112
2009	38.991
2010	39.37
2011	40.342
2012	40.717
2013	42.912
2014	43.935
2015	44.756
2016	44.784
2017	44.84
2018	45.192
2019	45.945
2020	46.553
2021	46.925
2022	47.632