Year	Percent
1991	34.647
1992	31.478
1993	30.994
1994	28.455
1995	25.188
1996	25.105
1997	26.249
1998	29.068
1999	28.649
2000	27.477
2001	27.894
2002	29.147
2003	29.268
2004	30.825
2005	31.768
2006	32.33
2007	33.298
2008	33.859
2009	34.927
2010	35.253
2011	35.34
2012	36.518
2013	36.15
2014	35.487
2015	35.887
2016	36.295
2017	35.543
2018	35.786
2019	36.163
2020	36.58
2021	36.989
2022	37.395