Year	Percent
1980	1.176
1981	1.207
1982	1.244
1983	1.271
1984	1.3
1985	1.309
1986	1.352
1987	1.432
1988	1.4
1989	1.354
1990	1.421
1991	1.401
1992	1.333
1993	1.413
1994	1.297
1995	1.341
1996	1.383
1997	1.428
1998	1.434
1999	1.339
2000	1.363
2001	1.251
2002	1.294
2003	1.313
2004	1.368
2005	1.423
2006	1.447
2007	1.442
2008	1.413
2009	1.352
2010	1.393
2011	1.487
2012	1.51
2013	1.585
2014	1.611
2015	1.654
2016	1.652
2017	1.712
2018	1.696
2019	1.601
2020	1.585
2021	1.576
2022	1.567
2023	1.566
2024	1.564