Year	Percent
1990	77.959
1991	78.083
1992	78.347
1993	78.679
1994	78.56
1995	77.87
1996	77.487
1997	75.97
1998	76.194
1999	76.454
2000	77.19
2001	77.003
2002	76.293
2003	76.204
2004	75.915
2005	76.502
2006	75.447
2007	75.62
2008	76.258
2009	77.441
2010	78.582
2011	78.624
2012	79.094
2013	79.09
2014	79.606
2015	79.599
2016	78.963
2017	79.146
2018	79.326
2019	79.504
2020	79.683
2021	79.862
2022	80.045
2023	80.231
2024	80.422
2025	80.617
2026	80.815
2027	81.018
2028	81.224
2029	81.429
2030	81.631
