Year	Percent
1990	71.54
1991	71.78
1992	72.018
1993	72.256
1994	72.492
1995	72.726
1996	72.96
1997	71.805
1998	70.62
1999	69.406
2000	68.165
2001	66.898
2002	65.606
2003	64.29
2004	62.952
2005	61.594
2006	60.218
2007	58.826
2008	57.419
2009	56
2010	55.849
2011	55.232
2012	54.288
2013	53.915
2014	53.63
2015	53.201
2016	52.914
2017	52.655
2018	52.397
2019	52.138
2020	51.88
2021	51.621
2022	51.363
2023	51.104
2024	50.846
2025	50.587
2026	50.329
2027	50.07
2028	49.812
2029	49.553
2030	49.295