Year	Number of
1990	152.85
1991	157.24
1992	162.85
1993	169.09
1994	175.9
1995	183.01
1996	190.28
1997	197.65
1998	206.35
1999	216.49
2000	228.63
2001	243.38
2002	261.33
2003	282.24
2004	304.19
2005	326.78
2006	337.57
2007	346.71
2008	359.66
2009	375.96
2010	397.54
2011	419.77
2012	447.73
2013	481.36
2014	512.63
2015	538.95
2016	567.76