Year	Number of
1990	218.03
1991	221.32
1992	227.74
1993	237.37
1994	244.64
1995	252.27
1996	259.33
1997	266.83
1998	273.2
1999	278.74
2000	286.35
2001	292.12
2002	302.49
2003	312.95
2004	325.35
2005	339.3
2006	353.21
2007	366.91
2008	381.53
2009	396.24
2010	412.64
2011	428.1
2012	443.84
2013	461.55
2014	478.29
2015	496.32
2016	518.5