Year	Number of
1990	98.07
1991	100.66
1992	104.34
1993	108.28
1994	112.34
1995	115.64
1996	119.86
1997	123.94
1998	126.31
1999	127.91
2000	130.5
2001	131.67
2002	135.58
2003	139.26
2004	144.18
2005	150.54
2006	154.85
2007	161.02
2008	167.01
2009	173.45
2010	180.98
2011	188.48
2012	196.51
2013	207.38
2014	221.1
2015	236.83
2016	251.36