Year	Percent
1991	43.455
1992	44.252
1993	45.186
1994	46.139
1995	47.181
1996	48.012
1997	48.956
1998	49.95
1999	50.976
2000	52.035
2001	52.356
2002	52.271
2003	52.303
2004	52.464
2005	52.687
2006	52.804
2007	53.033
2008	53.291
2009	53.59
2010	53.895
2011	54.341
2012	54.81
2013	55.265
2014	54.887
2015	54.686
2016	54.286
2017	54.19
2018	54.157
2019	54.325
2020	54.685
2021	55.034
2022	55.295