Year	Percent
1990	79.068
1991	78.612
1992	79.199
1993	79.576
1994	78.638
1995	79.491
1996	78.341
1997	78.716
1998	78.054
1999	78.092
2000	78.046
2001	77.497
2002	77.415
2003	76.984
2004	76.751
2005	76.349
2006	75.91
2007	75.864
2008	75.547
2009	75.575
2010	75.604
2011	75.511
2012	74.908
2013	74.774
2014	74.701
2015	74.331
2016	74.297
2017	74.143
2018	73.944
2019	73.709
2020	73.446
2021	73.196
2022	72.927
2023	72.632
2024	72.308
2025	71.955
2026	71.624
2027	71.273
2028	70.915
2029	70.573
2030	70.261