Year	Percent
1990	54.296
1991	54.639
1992	52.665
1993	52.151
1994	51.148
1995	49.959
1996	45.985
1997	38.951
1998	37.231
1999	35.485
2000	34.262
2001	30.96
2002	29.801
2003	28.999
2004	27.075
2005	26.244
2006	25.818
2007	24.991
2008	24.084
2009	24.053
2010	24.621
2011	24.335
2012	23.905
2013	24.159
2014	24.227
2015	24.743
2016	25.562
2017	25.235
2018	24.908
2019	24.582
2020	24.255
2021	23.929
2022	23.602
2023	23.276
2024	22.949
2025	22.622
2026	22.296
2027	21.969
2028	21.643
2029	21.316
2030	20.989