Year	Percent
1990	60.075
1991	59.935
1992	59.853
1993	59.631
1994	59.236
1995	58.729
1996	58.333
1997	58.244
1998	57.987
1999	57.76
2000	58.666
2001	59.566
2002	60.46
2003	61.347
2004	62.226
2005	63.098
2006	62.653
2007	62.261
2008	62.407
2009	62.264
2010	61.649
2011	61.158
2012	60.68
2013	60.044
2014	59.42
2015	58.783
2016	58.073
2017	58.144
2018	58.215
2019	58.286
2020	58.356
2021	58.427
2022	58.498
2023	58.569
2024	58.64
2025	58.711
2026	58.782
2027	58.853
2028	58.923
2029	58.994
2030	59.065