Year	Number
1996	14.48993
1997	14.15753
1998	13.91627
1999	13.80075
2000	13.44434
2001	12.84635
2002	12.57608
2003	12.97186
2004	11.14055
2005	10.31638
2006	9.57774
2007	7.31468
2008	7.35607
2009	7.34254
2010	7.1681
2011	7.08765
2012	7.02434
2013	7.27727
2014	7.32115
2015	7.54179
2016	5.91137