Year	Percent
1991	32.684
1992	33.126
1993	33.312
1994	32.894
1995	34.262
1996	33.784
1997	32.301
1998	32.459
1999	32.292
2000	33.849
2001	34.743
2002	33.813
2003	33.609
2004	33.049
2005	34.362
2006	36.661
2007	36.58
2008	33.705
2009	33.897
2010	27.924
2011	34.478
2012	33.423
2013	32.323
2014	30.484
2015	30.235
2016	30.752
2017	30.714
2018	30.85
2019	30.846
2020	30.911
2021	30.94
2022	30.933