Year	Number of
1990	221.95
1991	229.87
1992	237.94
1993	246.22
1994	255.06
1995	264.56
1996	270.78
1997	277.27
1998	284.09
1999	291.24
2000	298.82
2001	308.97
2002	319.89
2003	331.54
2004	343.74
2005	356.51
2006	368.63
2007	381.45
2008	394.89
2009	408.94
2010	423.78
2011	432.85
2012	442.33
2013	451.86
2014	461.54
2015	471.32
2016	481.19