Year	Percent
1990	71.91
1991	72.05
1992	72.221
1993	72.433
1994	72.426
1995	72.436
1996	72.449
1997	72.35
1998	72.07
1999	71.789
2000	71.315
2001	70.966
2002	70.667
2003	70.477
2004	70.266
2005	70.018
2006	69.784
2007	69.451
2008	69.114
2009	68.835
2010	68.437
2011	67.764
2012	67.127
2013	66.516
2014	65.925
2015	65.34
2016	64.918
2017	64.564
2018	64.242
2019	63.917
2020	63.567
2021	63.231
2022	62.871
2023	62.505
2024	62.159
2025	61.821
2026	61.557
2027	61.322
2028	61.107
2029	60.904
2030	60.722