Year	Percent
1991	29.998
1992	30.848
1993	30.174
1994	30.275
1995	30.671
1996	30.339
1997	25.885
1998	24.38
1999	27.404
2000	28.685
2001	32.588
2002	25.582
2003	22.985
2004	26.275
2005	28.601
2006	31.196
2007	32.334
2008	32.656
2009	28.559
2010	22.092
2011	23.785
2012	23.671
2013	20.836
2014	20.53
2015	19.171
2016	21.182
2017	21.558
2018	22.061
2019	22.526
2020	22.608
2021	22.567
2022	22.469