Year	Percent
1990	42.881
1991	42.599
1992	42.314
1993	42.003
1994	41.691
1995	41.365
1996	41.147
1997	41.338
1998	41.767
1999	41.614
2000	41.462
2001	41.355
2002	41.118
2003	40.822
2004	40.553
2005	40.373
2006	40.137
2007	39.86
2008	39.773
2009	39.823
2010	38.263
2011	37.7
2012	38.75
2013	38
2014	37.7
2015	35.1
2016	34.941
2017	34.779
2018	34.618
2019	34.457
2020	34.295
2021	34.134
2022	33.973
2023	33.811
2024	33.65
2025	33.489
2026	33.327
2027	33.166
2028	33.005
2029	32.844
2030	32.682