Year	Percent
1990	90.388
1991	90.455
1992	90.488
1993	90.357
1994	90.162
1995	89.959
1996	89.953
1997	89.993
1998	90.018
1999	90.178
2000	90.356
2001	90.468
2002	90.584
2003	90.671
2004	90.8
2005	90.875
2006	90.947
2007	91.024
2008	91.035
2009	91.116
2010	91.091
2011	91.103
2012	91.01
2013	90.955
2014	90.874
2015	90.807
2016	90.697
2017	90.658
2018	90.627
2019	90.607
2020	90.599
2021	90.599
2022	90.613
2023	90.64
2024	90.68
2025	90.732
2026	90.793
2027	90.865
2028	90.949
2029	91.05
2030	91.166
