Year	Percent
1990	44.117
1991	43.857
1992	43.481
1993	43.139
1994	42.655
1995	42.169
1996	41.685
1997	41.306
1998	41.335
1999	40.855
2000	39.628
2001	38.721
2002	36.779
2003	34.969
2004	33.257
2005	31.619
2006	30.258
2007	29.073
2008	28.063
2009	27.208
2010	26.469
2011	26.174
2012	25.893
2013	25.658
2014	25.4
2015	25.217
2016	25.118
2017	24.893
2018	24.687
2019	24.464
2020	24.209
2021	23.978
2022	23.721
2023	23.453
2024	23.201
2025	22.983
2026	22.842
2027	22.741
2028	22.655
2029	22.543
2030	22.382