Year	Percent
1991	33.7
1992	31.229
1993	29.976
1994	29.659
1995	27.138
1996	25.82
1997	24.58
1998	23.855
1999	23.155
2000	24.615
2001	22.834
2002	22.073
2003	18.573
2004	17.271
2005	16.842
2006	15.186
2007	13.343
2008	10.989
2009	12.013
2010	13.215
2011	12.717
2012	10.706
2013	11.61
2014	10.247
2015	8.873
2016	9.274
2017	8.904
2018	8.698
2019	8.473
2020	8.283
2021	8.109
2022	7.944