Year	Percent
1990	41.975
1991	42.891
1992	43.806
1993	44.722
1994	45.639
1995	46.559
1996	47.462
1997	48.366
1998	49.273
1999	50.183
2000	51.101
2001	52.022
2002	53.486
2003	53.873
2004	54.899
2005	55.433
2006	55.968
2007	55.619
2008	55.825
2009	56.015
2010	54.581
2011	53.132
2012	53.077
2013	52.976
2014	52.859
2015	53.378
2016	53.322
2017	53.204
2018	53.08
2019	52.945
2020	52.795
2021	52.649
2022	52.493
2023	52.322
2024	52.131
2025	51.915
2026	51.699
2027	51.461
2028	51.206
2029	50.938
2030	50.662