Year	Percent
1991	25.222
1992	31.404
1993	31.639
1994	29.971
1995	32.573
1996	32.99
1997	36.127
1998	38.415
1999	41.086
2000	43.984
2001	43.98
2002	38.349
2003	38.377
2004	34.969
2005	35.883
2006	34.654
2007	34.024
2008	32.779
2009	33.059
2010	35.8
2011	33.139
2012	33.352
2013	32.931
2014	32.36
2015	29.92
2016	27.846
2017	28.706
2018	28.401
2019	28.235
2020	28.101
2021	28.101
2022	28.096