Year	Percent
1991	17.856
1992	17.492
1993	17.975
1994	18.716
1995	18.02
1996	19.831
1997	20.602
1998	21.203
1999	21.116
2000	21.599
2001	23.118
2002	23.287
2003	23.54
2004	24.641
2005	25.523
2006	25.952
2007	26.67
2008	27.042
2009	27.484
2010	27.963
2011	28.705
2012	28.853
2013	28.983
2014	29.706
2015	30.809
2016	31.172
2017	31.159
2018	30.846
2019	29.505
2020	28.862
2021	27.723
2022	28.858