Year	Percent
1991	18.483
1992	18.092
1993	18.616
1994	18.491
1995	18.839
1996	18.807
1997	18.875
1998	18.822
1999	19.19
2000	19.548
2001	20.025
2002	20.198
2003	20.281
2004	20.602
2005	21.686
2006	21.471
2007	22.159
2008	22.096
2009	22.904
2010	23.142
2011	23.286
2012	23.883
2013	24.248
2014	25.383
2015	25.826
2016	26.693
2017	27.043
2018	27.584
2019	28.112
2020	28.715
2021	29.28
2022	29.852