Year	Percent
1990	38.907
1991	36.05
1992	36.339
1993	36.63
1994	36.921
1995	37.213
1996	37.507
1997	37.801
1998	38.096
1999	38.392
2000	38.689
2001	38.986
2002	39.285
2003	39.584
2004	39.884
2005	40.185
2006	40.487
2007	40.789
2008	41.092
2009	41.396
2010	41.7
2011	41.62
2012	41.195
2013	40.772
2014	40.35
2015	39.93
2016	40.36
2017	40.516
2018	40.672
2019	40.827
2020	40.983
2021	41.139
2022	41.294
2023	41.45
2024	41.606
2025	41.761
2026	41.917
2027	42.073
2028	42.228
2029	42.384
2030	42.54