Year	Percent
1990	35.302
1991	35.702
1992	34.079
1993	33.615
1994	33.556
1995	33.573
1996	33.959
1997	34.121
1998	34.563
1999	35.227
2000	35.446
2001	36.017
2002	36.554
2003	37.019
2004	38.258
2005	37.862
2006	37.974
2007	37.748
2008	38.391
2009	37.894
2010	37.785
2011	37.935
2012	39.163
2013	39.032
2014	39.4
2015	39.003
2016	39.635
2017	39.53
2018	39.421
2019	39.298
2020	39.151
2021	38.997
2022	38.829
2023	38.646
2024	38.447
2025	38.235
2026	38.039
2027	37.84
2028	37.634
2029	37.42
2030	37.193