Year	Percent
1990	55.213
1991	55.189
1992	54.985
1993	55.08
1994	55.582
1995	57.242
1996	58.483
1997	59.849
1998	61.187
1999	61.156
2000	61.264
2001	61.535
2002	62.391
2003	61.012
2004	61.173
2005	60.714
2006	61.03
2007	62.065
2008	63.241
2009	62.626
2010	61.79
2011	61.658
2012	61.598
2013	61.568
2014	61.349
2015	61.331
2016	60.883
2017	60.833
2018	60.799
2019	60.76
2020	60.698
2021	60.601
2022	60.49
2023	60.369
2024	60.249
2025	60.135
2026	60.036
2027	59.946
2028	59.858
2029	59.754
2030	59.623