Year	years
1978	67
1979	67.74
1980	67.24
1981	66.86
1982	66.44
1983	66.24
1984	66.55
1985	67.25
1986	67.66
1987	68.47
1988	68.68
1989	68.76
1990	68.92
1991	68.53
1992	68.51
1993	68.51
1994	68.59
1995	67.99
1996	68.4
1997	68.61
1998	69.01
1999	69.33
2000	68.87
2001	68.86
2002	69.27
2003	69.84
2004	70.4
2005	70.96
2006	71.28
2007	71.64
2008	71.89
2009	72.11
2010	72.36
2011	72.58
2012	72.8
2013	73.21
2014	73.33
2015	73.62
2016	74.21
2017	74.36
2018	74.17
2019	74.28
2020	74.13
2021	73.75
2022	73.41