Year	Percent
1990	40.508
1991	40.65
1992	40.621
1993	40.592
1994	40.563
1995	40.534
1996	40.504
1997	40.475
1998	40.446
1999	40.417
2000	40.388
2001	40.359
2002	40.33
2003	40.301
2004	40.272
2005	40.243
2006	40.214
2007	40.185
2008	40.156
2009	40.127
2010	40.098
2011	40.069
2012	40.04
2013	39.951
2014	39.86
2015	39.755
2016	39.66
2017	39.631
2018	39.601
2019	39.572
2020	39.543
2021	39.514
2022	39.484
2023	39.455
2024	39.426
2025	39.396
2026	39.367
2027	39.338
2028	39.309
2029	39.279
2030	39.25