Year	Percent
1991	19.47
1992	21.815
1993	20.686
1994	21.65
1995	20.901
1996	24.29
1997	23.243
1998	22.961
1999	24.782
2000	23.514
2001	23.588
2002	25.013
2003	22.898
2004	22.782
2005	21.876
2006	21.865
2007	21.946
2008	21.88
2009	23.645
2010	17.465
2011	17.436
2012	17.389
2013	17.358
2014	17.334
2015	17.466
2016	17.496
2017	17.542
2018	17.543
2019	17.531
2020	17.519
2021	17.515
2022	17.512