Year	Percent
1990	59.285
1991	59.007
1992	58.709
1993	56.895
1994	55.058
1995	54.539
1996	53.732
1997	52.709
1998	52.068
1999	55.398
2000	55.44
2001	54.276
2002	55.268
2003	55
2004	55.446
2005	55.889
2006	56.224
2007	56.785
2008	56.682
2009	56.86
2010	56.515
2011	56.932
2012	56.921
2013	56.749
2014	56.77
2015	56.753
2016	56.909
2017	56.64
2018	56.305
2019	55.958
2020	55.636
2021	55.297
2022	54.986
2023	54.697
2024	54.412
2025	54.121
2026	53.809
2027	53.506
2028	53.22
2029	52.966
2030	52.759