Year	Percent
1960	5.58852
1961	5.64803
1962	5.70388
1963	5.74376
1964	5.74658
1965	5.7222
1966	5.71505
1967	5.70216
1968	3.89942
1969	3.90985
1970	3.93656
1971	3.96334
1972	3.98526
1973	4.00262
1974	4.0053
1975	4.01338
1976	4.01652
1977	3.99938
1978	4.02273
1979	4.06158
1980	4.10248
1981	4.11763
1982	4.08957
1983	4.09103
1984	4.48544
1985	6.62356
1986	6.70445
1987	6.6972
1988	6.41273
1989	5.76413
1990	4.92966
1991	4.0075
1992	3.25161
1993	2.86279
1994	3.02071
1995	3.58206
1996	4.24651
1997	4.78885
1998	5.2967
1999	5.67795
2000	5.96187
2001	6.24106
2002	6.48129
2003	6.49942
2004	6.26637
2005	5.87317
2006	5.4456
2007	5.07866
2008	4.82516
2009	3.52501
2010	3.54207
2011	3.57182