Year	Percent
1991	32.792
1992	31.938
1993	31.295
1994	30.202
1995	29.64
1996	31.488
1997	31.569
1998	30.132
1999	30.991
2000	32.108
2001	31.152
2002	32.545
2003	33.651
2004	34.513
2005	33.958
2006	32.953
2007	31.607
2008	31.282
2009	29.078
2010	30.886
2011	31.071
2012	30.122
2013	29.999
2014	28.817
2015	30.132
2016	31.737
2017	33.798
2018	34.217
2019	34.361
2020	34.215
2021	34.042
2022	33.907