Year	Percent
1990	38.809
1991	38.838
1992	38.739
1993	38.673
1994	38.611
1995	38.528
1996	38.535
1997	38.529
1998	38.586
1999	38.564
2000	38.539
2001	38.692
2002	38.779
2003	38.867
2004	38.905
2005	38.973
2006	39.096
2007	39.178
2008	39.294
2009	39.312
2010	39.384
2011	39.43
2012	39.524
2013	39.55
2014	39.577
2015	39.563
2016	39.582
2017	39.646
2018	39.71
2019	39.774
2020	39.838
2021	39.903
2022	39.967
2023	40.031
2024	40.095
2025	40.159
2026	40.223
2027	40.287
2028	40.351
2029	40.416
2030	40.48