Year	years
1960	68.108
1961	68.291
1962	68.466
1963	68.897
1964	69.1
1965	69.249
1966	69.651
1967	69.781
1968	69.95
1969	70.409
1970	70.624
1971	70.819
1972	71.379
1973	71.557
1974	72.132
1975	72.251
1976	72.419
1977	72.53
1978	72.993
1979	73.155
1980	73.302
1981	73.433
1982	73.547
1983	73.708
1984	73.821
1985	73.884
1986	74.055
1987	74.406
1988	74.529
1989	74.399
1990	74.775
1991	74.903
1992	74.977
1993	75.078
1994	75.233
1995	75.254
1996	75.388
1997	75.489
1998	75.659
1999	75.749
2000	75.871
2001	76.019
2002	76.15
2003	76.314
2004	76.456
2005	76.602
2006	78.5
2007	79
2008	79.1
2009	80.1
2011	80.7
2012	80.7
2013	80.9
2014	81.1
2015	81.2
2016	81.1
2017	81.5