Year	Percent
1990	78.79
1991	77.691
1992	76.552
1993	75.373
1994	74.155
1995	72.899
1996	71.604
1997	70.274
1998	68.907
1999	68.824
2000	68.741
2001	68.658
2002	68.574
2003	68.491
2004	68.407
2005	68.323
2006	68.239
2007	68.155
2008	68.071
2009	67.986
2010	67.902
2011	67.817
2012	67.733
2013	67.648
2014	67.563
2015	68.143
2016	68.51
2017	68.399
2018	68.288
2019	68.177
2020	68.065
2021	67.954
2022	67.843
2023	67.732
2024	67.621
2025	67.509
2026	67.398
2027	67.287
2028	67.176
2029	67.065
2030	66.953