Year	Percent
1991	19.506
1992	19.281
1993	18.977
1994	18.955
1995	19.079
1996	19.011
1997	19.91
1998	21.179
1999	21.821
2000	22.517
2001	23.279
2002	24.173
2003	24.298
2004	24.381
2005	24.323
2006	24.169
2007	24.476
2008	25.51
2009	25.599
2010	25.873
2011	25.355
2012	24.902
2013	25.418
2014	25.061
2015	25.122
2016	25.16
2017	25.547
2018	25.528
2019	25.48
2020	25.49
2021	25.459
2022	25.418