Year	Percent
1990	77.999
1991	78.165
1992	78.276
1993	78.324
1994	78.257
1995	77.675
1996	77.284
1997	77.181
1998	76.95
1999	75.79
2000	74.59
2001	73.352
2002	72.077
2003	70.764
2004	69.416
2005	68.034
2006	66.62
2007	65.175
2008	63.701
2009	62.202
2010	60.678
2011	59.134
2012	57.571
2013	55.993
2014	54.403
2015	52.804
2016	51.199
2017	50.974
2018	50.75
2019	50.525
2020	50.3
2021	50.076
2022	49.851
2023	49.626
2024	49.402
2025	49.177
2026	48.952
2027	48.728
2028	48.503
2029	48.278
2030	48.053