Year	Percent
1990	82.231
1991	82.522
1992	82.866
1993	83.264
1994	83.396
1995	83.268
1996	82.719
1997	81.884
1998	81.137
1999	79.791
2000	77.614
2001	76.333
2002	73.955
2003	71.564
2004	69.048
2005	66.378
2006	64.14
2007	61.997
2008	59.981
2009	58.058
2010	56.163
2011	55.448
2012	54.716
2013	54.069
2014	53.381
2015	52.883
2016	52.591
2017	52.325
2018	52.132
2019	51.961
2020	51.787
2021	51.729
2022	51.68
2023	51.625
2024	51.555
2025	51.467
2026	51.46
2027	51.436
2028	51.392
2029	51.331
2030	51.26