Year	Number of
1990	112.97
1991	118.31
1992	124.25
1993	130.77
1994	137.64
1995	144.83
1996	153.85
1997	163.14
1998	173.02
1999	183.48
2000	194.67
2001	206.74
2002	219.53
2003	233.24
2004	247.7
2005	262.98
2006	283.39
2007	305.28
2008	328.21
2009	351.89
2010	376.04
2011	398.53
2012	421.31
2013	444.44
2014	470.29
2015	500.37
2016	533.35