Year	Number
1990	3.2692307692
1991	3.7051282051
1992	4.141025641
1993	4.5769230769
1994	5.0128205128
1995	5.4487179487
1996	5.8846153846
1997	6.3205128205
1998	6.7564102564
1999	7.1923076923
2000	7.6282051282
2001	8.0641025641
2002	8.5
2003	8.9358974359
2004	9.3717948718
2005	9.8076923077
2006	9.6153846154
2007	9.4230769231
2008	9.2307692308
2009	9.0384615385
2010	8.8461538462
2011	8.6538461538
2012	8.4615384615
2013	8.4615384615
2014	8.4615384615
2015	8.4615384615
2016	8.4615384615
2017	8.4615384615
2018	8.4615384615
2019	8.4615384615
2020	8.4615384615