Year	Percent
1990	64.868
1991	59.48
1992	58.461
1993	57.434
1994	56.402
1995	55.363
1996	54.32
1997	52.79
1998	51.254
1999	49.716
2000	48.179
2001	46.645
2002	45.117
2003	43.599
2004	42.092
2005	40.6
2006	37.759
2007	35
2008	31.5
2009	30.6
2010	27.4
2011	25.976
2012	24.6
2013	23.275
2014	22
2015	22.4
2016	22.8
2017	22.551
2018	22.301
2019	22.052
2020	21.803
2021	21.554
2022	21.304
2023	21.055
2024	20.806
2025	20.557
2026	20.307
2027	20.058
2028	19.809
2029	19.559
2030	19.31