Year	Percent
1990	47.577
1991	47.505
1992	47.448
1993	47.408
1994	47.363
1995	47.313
1996	47.292
1997	47.262
1998	47.239
1999	47.208
2000	47.227
2001	47.227
2002	47.233
2003	47.3
2004	47.538
2005	47.753
2006	47.993
2007	48.263
2008	48.558
2009	48.873
2010	49.201
2011	49.539
2012	49.888
2013	50.238
2014	50.308
2015	50.356
2016	50.326
2017	50.432
2018	50.529
2019	50.622
2020	50.716
2021	50.809
2022	50.908
2023	51.01
2024	51.117
2025	51.23
2026	51.347
2027	51.474
2028	51.613
2029	51.768
2030	51.942