Year	Percent
1990	82.253
1991	82.103
1992	81.943
1993	82.158
1994	82.363
1995	82.558
1996	82.736
1997	82.905
1998	83.808
1999	84.528
2000	84.682
2001	84.884
2002	85.057
2003	85.174
2004	85.231
2005	85.238
2006	84.863
2007	84.446
2008	83.959
2009	84.305
2010	83.932
2011	83.992
2012	84.045
2013	84.085
2014	83.728
2015	82.719
2016	81.954
2017	81.802
2018	81.642
2019	81.491
2020	81.358
2021	81.227
2022	81.12
2023	81.021
2024	80.909
2025	80.772
2026	80.599
2027	80.409
2028	80.212
2029	80.025
2030	79.859