Year	Percent
1991	77.031
1992	71.767
1993	68.461
1994	70.803
1995	70.754
1996	71.045
1997	66.704
1998	66.489
1999	67.277
2000	60.155
2001	62.97
2002	59.606
2003	58.115
2004	50.657
2005	46.167
2006	43.529
2007	42.585
2008	41.894
2009	37.777
2010	39.188
2011	39.258
2012	37.088
2013	35.551
2014	32.759
2015	30.995
2016	28.586
2017	28.794
2018	27.547
2019	26.792
2020	25.965
2021	25.155
2022	24.332