Year	Percent
1991	56.314
1992	55.009
1993	53.116
1994	52.461
1995	51.694
1996	50.822
1997	49.929
1998	49.523
1999	48.475
2000	47.089
2001	46.071
2002	44.867
2003	42.753
2004	41.619
2005	39.54
2006	37.232
2007	35.001
2008	33.296
2009	31.58
2010	29.906
2011	28.092
2012	26.682
2013	25.368
2014	24.105
2015	22.788
2016	21.449
2017	20.497
2018	19.282
2019	18.184
2020	17.138
2021	16.16
2022	15.249