Year	Percent
1991	18.178
1992	20.22
1993	21.976
1994	20.728
1995	21.975
1996	21.166
1997	19.171
1998	19.601
1999	20.195
2000	21.751
2001	22.252
2002	20.532
2003	19.904
2004	18.576
2005	17.511
2006	18.645
2007	19.625
2008	16.027
2009	15.659
2010	14.876
2011	16.542
2012	17.119
2013	17.122
2014	16.992
2015	16.914
2016	16.299
2017	16.277
2018	16.312
2019	16.171
2020	16.097
2021	15.977
2022	15.839