Year	Percent
1990	79.018
1991	79.076
1992	78.195
1993	77.281
1994	76.331
1995	75.348
1996	74.335
1997	73.29
1998	72.213
1999	71.108
2000	69.973
2001	68.815
2002	67.63
2003	66.421
2004	65.184
2005	63.923
2006	62.636
2007	62.28
2008	61.919
2009	61.556
2010	61.192
2011	60.837
2012	60.484
2013	60.134
2014	59.787
2015	59.837
2016	59.901
2017	59.677
2018	59.448
2019	59.214
2020	58.975
2021	58.742
2022	58.505
2023	58.268
2024	58.037
2025	57.813
2026	57.605
2027	57.404
2028	57.209
2029	57.017
2030	56.828