Year	Percent
1991	33.721
1992	34.623
1993	36.131
1994	37.572
1995	40.176
1996	40.865
1997	42.347
1998	44.148
1999	47.741
2000	41.696
2001	44.98
2002	47.111
2003	49.411
2004	50.215
2005	52.347
2006	54.216
2007	56.339
2008	57.041
2009	57.851
2010	59.365
2011	57.284
2012	56.9
2013	57.273
2014	54.512
2015	52.066
2016	50.905
2017	51.717
2018	52.254
2019	52.812
2020	53.382
2021	53.967
2022	54.566