Year	Percent
1990	60.701
1991	63.016
1992	64.209
1993	66.288
1994	67.086
1995	68.011
1996	68.749
1997	69.571
1998	70.309
1999	72.722
2000	72.985
2001	70.62
2002	71.842
2003	72.965
2004	74.192
2005	76.773
2006	76.961
2007	78.035
2008	78.983
2009	79.242
2010	80.408
2011	78.74
2012	79.156
2013	79.741
2014	80.58
2015	80.213
2016	79.861
2017	80.147
2018	80.437
2019	80.728
2020	81.02
2021	81.312
2022	81.604
2023	81.897
2024	82.189
2025	82.477
2026	82.762
2027	83.045
2028	83.323
2029	83.598
2030	83.867