Year	Number of
1990	329.91
1991	330.22
1992	329.57
1993	328.47
1994	328.2
1995	329.39
1996	334.64
1997	341.97
1998	351.77
1999	360.18
2000	365.82
2001	376.26
2002	394.54
2003	409.54
2004	422.36
2005	436.05
2006	450.49
2007	465.41
2008	480.18
2009	491.14
2010	499.78
2011	513.45
2012	537.49
2013	552.52
2014	567.69
2015	584.5
2016	608.08