Year	Percent
1991	22.716
1992	23.309
1993	23.816
1994	23.685
1995	22.884
1996	23.312
1997	22.94
1998	21.496
1999	22.296
2000	21.471
2001	21.943
2002	21.546
2003	20.698
2004	20.946
2005	20.121
2006	21.6
2007	22.474
2008	21.781
2009	22.087
2010	22.383
2011	23.338
2012	24.179
2013	25.297
2014	25.906
2015	26.342
2016	26.644
2017	26.771
2018	26.846
2019	26.897
2020	28.156
2021	28.869
2022	29.035