Year	Number of
1990	43.2
1991	46.36
1992	49.48
1993	53.21
1994	57.25
1995	61.99
1996	66.95
1997	72.12
1998	78.06
1999	84.68
2000	92.85
2001	100.82
2002	109.55
2003	119.69
2004	128.44
2005	138.41
2006	145
2007	151.63
2008	157.87
2009	165.05
2010	173.02
2011	179
2012	183.66
2013	189.48
2014	196
2015	202.76
2016	210.34