Year	Number of
1990	89.06
1991	91.87
1992	94.97
1993	98.34
1994	101.95
1995	105.85
1996	109.16
1997	112.77
1998	116.68
1999	120.92
2000	125.53
2001	129.99
2002	134.87
2003	140.13
2004	145.71
2005	151.62
2006	158
2007	164.63
2008	171.73
2009	179.29
2010	187.44
2011	196.44
2012	206.2
2013	216.62
2014	227.77
2015	239.65
2016	251.81