Year	Number of
1990	71.42
1991	73.91
1992	76.38
1993	78.95
1994	81.54
1995	84.22
1996	87.63
1997	91.18
1998	94.9
1999	98.67
2000	102.49
2001	106.55
2002	110.53
2003	114.71
2004	119.12
2005	123.92
2006	128.05
2007	132.38
2008	137.1
2009	142.17
2010	147.67
2011	152.99
2012	158.79
2013	164.58
2014	170.8
2015	177.5
2016	186.23