Year	Percent
1991	57.616
1992	53.793
1993	54.089
1994	51.276
1995	54.018
1996	55.406
1997	56.62
1998	56.434
1999	56.163
2000	56.839
2001	57.15
2002	57.898
2003	58.277
2004	58.285
2005	59.042
2006	59.815
2007	60.801
2008	62.144
2009	62.476
2010	61.886
2011	62.419
2012	63.127
2013	63.945
2014	64.776
2015	65.078
2016	66.033
2017	66.36
2018	66.864
2019	67.357
2020	68.011
2021	68.668
2022	69.335