Year	Percent
1991	36.175
1992	34.932
1993	36.822
1994	37.217
1995	38.632
1996	38.622
1997	41.457
1998	35.766
1999	25.066
2000	33.095
2001	40.722
2002	48.936
2003	52.949
2004	57.022
2005	60.581
2006	59.942
2007	61.641
2008	60.922
2009	63.92
2010	65.666
2011	66.791
2012	66.73
2013	67.055
2014	67.833
2015	69.103
2016	68.477
2017	68.845
2018	69.486
2019	70.12
2020	70.993
2021	71.407
2022	71.849