Year	Number
1963	1.119053657283622
1964	1.1808524666423958
1965	1.2524392545657157
1966	1.5674720766241061
1967	1.4580059048870033
1968	1.2646303978791291
1969	1.316737754175262
1970	1.2420607653408886
1971	0.945842455138669
1972	0.9902695061466723
1973	0.9491830086366351
1974	1.0020187812645227
1975	1.1142553572200609
1976	1.153640043736689
1977	1.0287959720510775
1978	0.8397160511521911
1979	0.9748907908140341
1980	1.1249897035877905
1981	1.2169313057560889
1982	1.2728842953708126
1983	1.287486364521995
1984	1.2322271043990498
1985	1.0271877042757143
1986	1.087432774433942
1987	1.118675026043395
1988	1.170583709846125
1989	1.2573821074155758
1990	1.1410768724437867
1991	1.1775316585650109
1992	1.1639138975758783
1993	1.049845921885345
1994	1.0554391112794184
1995	1.0454157975321796
1996	1.0315939021452138
1997	1.1645614400397186
1998	1.279624697391501
1999	1.3360278371691354
2000	1.2225556330785308
2001	1.318139006406861
2002	1.2072141779751784
2003	1.1441255355737792
2004	1.0726548322332667
2005	1.1185570985166844
2006	1.190912960016004
2007	1.1882331944609779
2008	1.3272742140220155
2009	1.3289063477869625
2010	1.2783544793693051
2011	1.445842264214277
2012	1.4306049417575821
2013	1.4266305882454966
2014	1.5460815960759202
2015	1.5023466673677206
2016	1.6205572997267654
2017	1.4738814876518622
2018	1.5264913185995423
2019	1.62424786821469
2020	1.4031252605364692