Year	Number of
1990	46.87
1991	49.81
1992	52.96
1993	56.51
1994	60.28
1995	64.33
1996	69.32
1997	74.63
1998	80.6
1999	86.85
2000	93.46
2001	99.62
2002	106.08
2003	112.85
2004	120.36
2005	128.78
2006	136.81
2007	145.55
2008	155.12
2009	165.38
2010	176.38
2011	188.15
2012	200.77
2013	214.46
2014	229.23
2015	245.22
2016	262.67