Year	Percent
1991	20.529
1992	20.264
1993	19.835
1994	18.496
1995	19.516
1996	19.582
1997	20.145
1998	18.253
1999	18.283
2000	19.481
2001	19.464
2002	21.603
2003	21.657
2004	21.318
2005	21.385
2006	22.036
2007	22.916
2008	22.012
2009	22.43
2010	23.986
2011	24.509
2012	25.715
2013	26.063
2014	25.586
2015	26.608
2016	26.192
2017	26.329
2018	26.54
2019	26.641
2020	26.728
2021	26.789
2022	26.838