Year	Percent
1990	69.312
1991	69.505
1992	69.565
1993	69.462
1994	69.406
1995	69.413
1996	69.177
1997	69.057
1998	68.919
1999	68.936
2000	68.618
2001	68.519
2002	68.448
2003	67.921
2004	65.958
2005	65.139
2006	64.311
2007	63.475
2008	62.63
2009	61.778
2010	60.918
2011	60.052
2012	59.179
2013	58.3
2014	58.044
2015	57.986
2016	58.261
2017	57.929
2018	57.598
2019	57.266
2020	56.934
2021	56.603
2022	56.271
2023	55.94
2024	55.608
2025	55.277
2026	54.945
2027	54.614
2028	54.282
2029	53.951
2030	53.619