Year	Percent
1991	37.329
1992	43.954
1993	51.252
1994	49.476
1995	49.259
1996	47.123
1997	44.995
1998	46.135
1999	44.148
2000	43.492
2001	43.613
2002	41.889
2003	39.273
2004	38.248
2005	35.169
2006	32.694
2007	30.354
2008	30.834
2009	34.175
2010	31.676
2011	33.141
2012	31.348
2013	29.021
2014	29.963
2015	31.25
2016	30.449
2017	30.494
2018	29.482
2019	28.885
2020	28.234
2021	27.587
2022	26.965