Year	Number
1977	1.1685493297330505
1978	2.2629173821393445
1979	4.043393022644984
1980	2.6583231888707943
1981	1.8675686073462476
1982	1.7496934407448435
1983	2.0562954589959834
1984	2.057667270080589
1985	2.680835868804169
1986	2.44684086370593
1987	2.6984410037860416
1988	2.263065731679021
1989	1.637719912823471
1990	1.5502558250085376
1991	1.389241803321556
1992	1.7699721382779108
1993	3.2279015161717477
1994	2.479525004693616
2009	2.6135260378768073
2010	1.3318070499742
2011	0.8315141118228552
2012	0.7953856497164091
2013	0.6562368442408469
2014	0.5284273498673907
2015	0.6876047134334431
2016	0.7417069454268167
2017	0.5310023044296474
2018	0.1310598430973754
2019	0.31547741943746954
2020	0.06714702198244303