Year	Percent
1990	78.747
1991	78.557
1992	79.928
1993	81.194
1994	80.966
1995	81.746
1996	81.403
1997	81.045
1998	81.072
1999	81.055
2000	80.945
2001	80.826
2002	80.698
2003	80.702
2004	81.382
2005	81.105
2006	80.701
2007	80.911
2008	82.91
2009	83.109
2010	82.641
2011	81.235
2012	81.798
2013	82.032
2014	81.375
2015	81.29
2016	81.166
2017	81.185
2018	81.204
2019	81.213
2020	81.208
2021	81.197
2022	81.177
2023	81.149
2024	81.11
2025	81.063
2026	81.013
2027	80.957
2028	80.899
2029	80.844
2030	80.796