Year	Percent
1991	18.618
1992	18.922
1993	19.142
1994	19.334
1995	19.587
1996	19.734
1997	20.105
1998	20.504
1999	20.918
2000	21.439
2001	21.719
2002	21.967
2003	22.264
2004	22.651
2005	23.065
2006	23.93
2007	24.719
2008	25.49
2009	25.859
2010	26.095
2011	26.189
2012	26.472
2013	26.551
2014	26.572
2015	26.624
2016	26.256
2017	26.303
2018	26.307
2019	26.297
2020	26.269
2021	26.138
2022	26.008