Year	Number
1990	7.2115384615
1991	7.1621394231
1992	7.1127403846
1993	7.0633413462
1994	7.0139423077
1995	6.9645432692
1996	7.7805288462
1997	8.5965144231
1998	9.4125
1999	10.2284855769
2000	11.0444711538
2001	10.5195913462
2002	9.9947115385
2003	9.4698317308
2004	8.9449519231
2005	8.4200721154
2006	7.6467548077
2007	7.4984375
2008	7.3501201923
2009	7.2018028846
2010	7.0534855769
2011	6.9051682692
2012	6.7568509615
2013	6.6085336538
2014	6.4602163462
2015	5.5288461538
2016	6.5625
2017	6.5564903846
2018	5.7572115385
2019	6.796875
2020	4.7235576923