Year	Number of
1990	318.94
1991	320.48
1992	322.39
1993	324.77
1994	327.27
1995	330.01
1996	329.87
1997	329.73
1998	329.79
1999	330.08
2000	330.76
2001	337.38
2002	344.38
2003	351.93
2004	359.83
2005	368.26
2006	384.05
2007	400.66
2008	418.81
2009	438.02
2010	458.52
2011	478.11
2012	498.77
2013	520.63
2014	543.7
2015	568.1
2016	594.3