Year	Percent
1991	29.453
1992	28.165
1993	27.904
1994	25.433
1995	23.135
1996	21.698
1997	21.605
1998	22.446
1999	21.497
2000	20.966
2001	20.947
2002	19.563
2003	20.381
2004	19.729
2005	20.76
2006	19.342
2007	19.746
2008	18.983
2009	17.668
2010	16.613
2011	16.398
2012	16.162
2013	16.188
2014	16.188
2015	16.466
2016	15.579
2017	15.418
2018	15.055
2019	14.678
2020	14.337
2021	14.019
2022	13.75