Year	Number
1979	3.627307086688086
1980	3.2455832060078014
1981	2.3201402675899954
1982	2.8164500593390542
1983	3.317047252120618
1984	3.4306800211913093
1985	3.411046493141486
1986	3.679880441950703
1987	3.936051601510577
1988	4.576789065993229
1989	3.9117892897901934
1990	4.18158946355846
1991	4.16377257211106
1992	4.138544577467444
1993	3.545043308638666
1994	3.2949742689191046
1995	3.5324474596230275
1996	3.8444799155662612
1997	3.365572846110556
1998	4.228268871819465
1999	4.422169962453182
2000	4.071993590765885
2001	3.5878917805787034
2002	3.534676618599213
2003	3.257321252430162
2004	3.6663641318045186
2005	2.724908452595485
2006	2.8431117491125923
2007	3.268099373428357
2008	2.132989515314191
2009	4.266902735633859
2010	4.412566770894442
2011	4.717249489170814
2012	5.234766427882401
2013	5.187686905723434
2014	5.117060506829143
2015	5.796682600469793
2016	5.717558452848542
2017	6.290296585595191
2018	6.26363838957554
2019	6.554791872399688
2020	10.286840366789919
2021	10.157603548385977
2022	8.247604786079979