Year	Percent
1991	17.209
1992	17.583
1993	17.936
1994	17.738
1995	14.752
1996	19.345
1997	17.674
1998	18.612
1999	19.667
2000	13.481
2001	19.457
2002	19.08
2003	18.743
2004	19.706
2005	18.947
2006	18.77
2007	19.304
2008	19.007
2009	18.387
2010	18.322
2011	18.621
2012	18.965
2013	18.503
2014	18.403
2015	17.995
2016	17.993
2017	17.992
2018	17.989
2019	17.985
2020	17.982
2021	17.979
2022	17.975