Year	Percent
1991	41.375
1992	39.434
1993	40.341
1994	38.143
1995	38.89
1996	38
1997	35.194
1998	34.983
1999	34.96
2000	35.597
2001	38.757
2002	37.083
2003	37.936
2004	36.337
2005	34.333
2006	34.669
2007	35.138
2008	36.322
2009	35
2010	34.817
2011	29.829
2012	27.036
2013	24.374
2014	27.796
2015	29.069
2016	28.984
2017	31.86
2018	31.78
2019	31.794
2020	31.853
2021	31.364
2022	30.767