Year	Percent
1990	48.742
1991	45.038
1992	41.371
1993	41.228
1994	41.762
1995	39.342
1996	38.919
1997	38.429
1998	44.839
1999	40.988
2000	40.34
2001	40.281
2002	40.248
2003	40.225
2004	40.191
2005	40.137
2006	40.069
2007	39.968
2008	39.847
2009	39.728
2010	37.777
2011	37.644
2012	36.012
2013	39.149
2014	38.404
2015	38.43
2016	38.526
2017	38.473
2018	38.401
2019	38.323
2020	38.248
2021	38.195
2022	38.144
2023	38.1
2024	38.065
2025	38.046
2026	38.061
2027	38.094
2028	38.135
2029	38.171
2030	38.193