Year	Percent
1991	14.72
1992	16.479
1993	17.209
1994	18.713
1995	20.144
1996	20.598
1997	15.487
1998	16.89
1999	18.261
2000	18.981
2001	19.181
2002	20.101
2003	21.85
2004	21.529
2005	20.313
2006	20.181
2007	20.437
2008	20.255
2009	20.803
2010	21.894
2011	21.967
2012	22.216
2013	21.215
2014	21.955
2015	20.904
2016	20.272
2017	20.589
2018	20.438
2019	20.39
2020	20.394
2021	20.41
2022	20.412