Year	Number of
1990	122.61
1991	125.02
1992	128.89
1993	131.59
1994	134.56
1995	136.78
1996	141.46
1997	143.89
1998	146.36
1999	150.97
2000	157.34
2001	163.22
2002	168.23
2003	171.03
2004	171.93
2005	175.2
2006	178.14
2007	183.73
2008	189.03
2009	191.55
2010	196.25
2011	202.15
2012	210.89
2013	222.78
2014	225.11
2015	227.5
2016	231.4