Year	Percent
1990	52.95
1991	53.779
1992	54.677
1993	55.313
1994	55.874
1995	56.466
1996	56.663
1997	56.837
1998	56.985
1999	57.112
2000	57.228
2001	57.364
2002	57.59
2003	57.898
2004	58.671
2005	59.247
2006	59.897
2007	60.274
2008	60.313
2009	59.763
2010	59.532
2011	59.675
2012	59.725
2013	59.466
2014	59.091
2015	58.7
2016	58.036
2017	57.661
2018	57.332
2019	57.093
2020	56.965
2021	56.692
2022	56.504
2023	56.414
2024	56.418
2025	56.504
2026	56.582
2027	56.736
2028	56.954
2029	57.216
2030	57.501