Year	Percent
1960	0.18294
1961	0.31287
1962	0.87319
1963	1.04308
1964	0.94336
1965	0.82958
1966	1.26896
1967	2.92406
1968	2.85044
1969	2.92465
1970	3.12558
1971	3.08796
1972	2.13834
1973	2.24993
1974	2.30047
1975	2.2813
1976	2.14291
1977	1.98224
1978	2.04285
1979	1.9506
1980	1.76538
1981	1.71352
1982	1.23258
1983	0.99709
1984	0.90525
1985	0.44482
1986	0.31516
1987	0.23339
1988	-0.20686
1989	-0.17419
1990	0.30419
1991	0.82757
1992	1.06697
1993	0.88136
1994	0.77428
1995	0.88957
1996	1.1771
1997	1.42479
1998	1.46158
1999	1.54574
2000	1.7481
2001	2.00378
2002	2.10513
2003	2.09058
2004	2.2895
2005	2.63446
2006	3.12667
2007	3.22296
2008	2.368
2009	1.34389
2010	0.8704
2011	0.7605
2012	0.74717
2013	0.84732
2014	1.05071
2015	1.26196
2016	1.44655
2017	1.55214