Year	Percent
1991	35.169
1992	37.044
1993	35.787
1994	36.089
1995	33.736
1996	34.665
1997	36.029
1998	36.139
1999	38.384
2000	40.079
2001	40.251
2002	40.84
2003	40.52
2004	41.201
2005	42.723
2006	43.787
2007	44.605
2008	44.124
2009	45.781
2010	46.339
2011	46.317
2012	47.958
2013	47.844
2014	48.994
2015	49.622
2016	48.776
2017	49.39
2018	49.459
2019	49.549
2020	49.609
2021	49.577
2022	49.563