Year	Percent
1990	35.869
1991	35.309
1992	34.692
1993	33.823
1994	33.956
1995	34.132
1996	34.71
1997	34.865
1998	34.811
1999	35.14
2000	35.526
2001	35.751
2002	35.957
2003	36.328
2004	36.769
2005	38.278
2006	39.786
2007	41.086
2008	41.609
2009	42.643
2010	42.287
2011	42.301
2012	42.295
2013	42.233
2014	42.02
2015	41.926
2016	41.57
2017	41.46
2018	41.308
2019	41.124
2020	40.911
2021	40.699
2022	40.47
2023	40.213
2024	39.915
2025	39.566
2026	39.208
2027	38.812
2028	38.398
2029	38.002
2030	37.645