Year	Number of
1990	137.49
1991	145.16
1992	153.76
1993	164.12
1994	174.62
1995	185.4
1996	195.6
1997	205.44
1998	213.61
1999	222.79
2000	225.56
2001	228.94
2002	233.06
2003	238.42
2004	242.78
2005	251.67
2006	262.39
2007	272.18
2008	283.84
2009	295.58
2010	307.74
2011	320.37
2012	332.9
2013	348.22
2014	364.24
2015	381.52
2016	400