Year	Percent
1990	43.919
1991	44.855
1992	45.656
1993	46.269
1994	45.578
1995	44.886
1996	44.202
1997	43.512
1998	42.817
1999	42.121
2000	41.431
2001	40.756
2002	40.094
2003	39.959
2004	40.22
2005	40.328
2006	41.34
2007	42.562
2008	43.536
2009	44.515
2010	45.386
2011	46.411
2012	47.246
2013	48.002
2014	48.664
2015	49.31
2016	49.888
2017	50.089
2018	50.288
2019	50.481
2020	50.67
2021	50.856
2022	51.037
2023	51.22
2024	51.408
2025	51.604
2026	51.809
2027	52.022
2028	52.24
2029	52.458
2030	52.674