Year	Percent
1990	37.192
1991	36.734
1992	37.095
1993	37.062
1994	36.966
1995	36.999
1996	36.817
1997	36.696
1998	36.389
1999	36.183
2000	36.322
2001	35.714
2002	35.76
2003	35.473
2004	35.6
2005	38.534
2006	41.553
2007	44.638
2008	47.764
2009	50.908
2010	54.045
2011	52.705
2012	51.361
2013	50.016
2014	48.67
2015	48.423
2016	48.152
2017	48.738
2018	49.323
2019	49.908
2020	50.494
2021	51.079
2022	51.665
2023	52.25
2024	52.835
2025	53.421
2026	54.006
2027	54.591
2028	55.177
2029	55.762
2030	56.348