Year	Percent
1990	41.767
1991	41.05
1992	38.706
1993	38.673
1994	38.156
1995	37.905
1996	35.632
1997	34.01
1998	32.459
1999	30.945
2000	29.471
2001	28.039
2002	26.65
2003	25.305
2004	24.007
2005	22.754
2006	21.549
2007	20.39
2008	18.25
2009	17.81
2010	19.08
2011	17.3
2012	15.4
2013	14.997
2014	14.626
2015	14.651
2016	14.683
2017	14.397
2018	14.111
2019	13.825
2020	13.539
2021	13.253
2022	12.967
2023	12.681
2024	12.395
2025	12.108
2026	11.822
2027	11.536
2028	11.25
2029	10.964
2030	10.678