Year	Percent
1990	77.365
1991	77.808
1992	78.243
1993	78.305
1994	78.05
1995	77.866
1996	77.976
1997	77.988
1998	77.569
1999	77.142
2000	76.629
2001	75.972
2002	75.186
2003	74.558
2004	73.801
2005	73.548
2006	73.331
2007	73.541
2008	73.27
2009	72.619
2010	72.112
2011	71.441
2012	70.952
2013	70.861
2014	70.793
2015	70.76
2016	70.931
2017	70.546
2018	70.199
2019	69.877
2020	69.568
2021	69.282
2022	69.02
2023	68.772
2024	68.524
2025	68.267
2026	68.005
2027	67.737
2028	67.459
2029	67.17
2030	66.866