Year	Percent
1990	53.793
1991	53.765
1992	53.655
1993	53.395
1994	53.394
1995	53.328
1996	53.171
1997	53.062
1998	52.811
1999	52.604
2000	52.367
2001	52.246
2002	52.129
2003	52.066
2004	51.985
2005	51.907
2006	51.925
2007	50.729
2008	49.532
2009	48.336
2010	47.141
2011	45.95
2012	45.943
2013	45.913
2014	45.878
2015	45.818
2016	45.749
2017	45.487
2018	45.225
2019	44.964
2020	44.702
2021	44.441
2022	44.179
2023	43.917
2024	43.656
2025	43.394
2026	43.132
2027	42.871
2028	42.609
2029	42.348
2030	42.086