Year	Percent
1990	43.451
1991	43.433
1992	43.369
1993	43.488
1994	43.49
1995	40.05
1996	36.705
1997	33.484
1998	30.409
1999	27.5
2000	29.399
2001	31.371
2002	33.414
2003	35.521
2004	37.685
2005	39.9
2006	39.863
2007	39.805
2008	39.709
2009	39.563
2010	39.42
2011	39.232
2012	39.019
2013	38.816
2014	38.603
2015	38.38
2016	38.185
2017	38.577
2018	38.968
2019	39.36
2020	39.751
2021	40.143
2022	40.534
2023	40.926
2024	41.317
2025	41.709
2026	42.101
2027	42.492
2028	42.884
2029	43.275
2030	43.667