Year	Number of
1990	70.94
1991	73.35
1992	75.9
1993	78.54
1994	81.31
1995	84.37
1996	86.98
1997	89.85
1998	92.88
1999	96.07
2000	99.58
2001	102.4
2002	105.55
2003	108.87
2004	112.29
2005	116
2006	119.63
2007	123.07
2008	126.81
2009	130.71
2010	135.05
2011	139.36
2012	144.1
2013	149.01
2014	154.12
2015	159.47
2016	165.39