Year	Number of
1990	55.4
1991	58.48
1992	61.74
1993	65.27
1994	69.15
1995	73.5
1996	80.01
1997	87.47
1998	95.9
1999	105.24
2000	115.58
2001	122.15
2002	128.76
2003	135.52
2004	142.63
2005	150.32
2006	153.92
2007	157.76
2008	161.98
2009	166.53
2010	171.43
2011	176.76
2012	182.55
2013	188.63
2014	195.07
2015	201.86
2016	208.54