Year	Percent
1990	62.076
1991	62.212
1992	62.381
1993	62.236
1994	62.044
1995	61.829
1996	58.71
1997	59.541
1998	58.443
1999	58.505
2000	57.869
2001	56.607
2002	50.604
2003	48.518
2004	48.075
2005	46.313
2006	47.243
2007	46.835
2008	46.149
2009	45.872
2010	46.331
2011	46.15
2012	46.28
2013	46.003
2014	46.146
2015	45.194
2016	44.476
2017	44.104
2018	43.72
2019	43.338
2020	42.966
2021	42.607
2022	42.265
2023	41.928
2024	41.58
2025	41.209
2026	40.811
2027	40.395
2028	39.959
2029	39.509
2030	39.048