Year	Percent
1991	20.927
1992	21.308
1993	21.516
1994	21.482
1995	21.237
1996	21.363
1997	21.583
1998	21.802
1999	22.097
2000	22.344
2001	22.234
2002	22.331
2003	22.586
2004	22.851
2005	23.025
2006	23.503
2007	24.06
2008	22.473
2009	22.518
2010	23.435
2011	23.974
2012	24.096
2013	24.11
2014	24.031
2015	24.047
2016	24.229
2017	24.228
2018	24.424
2019	24.639
2020	24.728
2021	24.573
2022	24.409