Year	Percent
1991	32.709
1992	32.837
1993	31.048
1994	33.069
1995	33.094
1996	32.802
1997	31.532
1998	26.58
1999	27.354
2000	28.419
2001	27.533
2002	28.717
2003	27.761
2004	28.548
2005	27.197
2006	25.616
2007	24.615
2008	21.844
2009	20.873
2010	20.442
2011	20.611
2012	21.964
2013	22.147
2014	23.83
2015	25.077
2016	25.543
2017	25.359
2018	25.141
2019	24.927
2020	24.552
2021	24.095
2022	23.545