Year	Percent
1991	42.152
1992	50.321
1993	58.156
1994	63.569
1995	71.943
1996	74.068
1997	62.251
1998	59.581
1999	55.668
2000	51.789
2001	52.004
2002	52.353
2003	57.148
2004	53.887
2005	54.754
2006	49.004
2007	51.35
2008	50.783
2009	52.071
2010	47.492
2011	45.9
2012	46.071
2013	44.325
2014	43.068
2015	42.887
2016	43.562
2017	42.406
2018	41.75
2019	41.01
2020	40.197
2021	39.301
2022	38.46