Year	Percent
1991	31.131
1992	31.034
1993	30.746
1994	32.717
1995	31.648
1996	30.299
1997	38.085
1998	41.234
1999	41.788
2000	38.007
2001	32.037
2002	27.094
2003	29.519
2004	28.359
2005	30.194
2006	27.26
2007	27.057
2008	27.459
2009	28.039
2010	29.113
2011	29.118
2012	30.829
2013	32.041
2014	33.029
2015	32.758
2016	33.532
2017	33.594
2018	33.654
2019	33.866
2020	34
2021	34.108
2022	34.2