Year	Percent
1990	43.874
1991	43.681
1992	43.386
1993	43.121
1994	42.778
1995	42.475
1996	42.289
1997	42.223
1998	42.485
1999	42.337
2000	41.63
2001	41.098
2002	40.65
2003	40.235
2004	39.809
2005	39.331
2006	38.813
2007	38.264
2008	37.705
2009	37.18
2010	36.726
2011	36.595
2012	36.583
2013	36.665
2014	36.665
2015	36.648
2016	36.574
2017	36.316
2018	36.016
2019	35.661
2020	35.249
2021	34.79
2022	34.285
2023	33.787
2024	33.371
2025	33.073
2026	32.894
2027	32.841
2028	32.862
2029	32.865
2030	32.788