Year	Number of
1990	70.1
1991	71.76
1992	73.56
1993	74.85
1994	77.3
1995	78.7
1996	79.71
1997	80.93
1998	82.79
1999	86.18
2000	89.17
2001	93.22
2002	97
2003	100.94
2004	106.11
2005	111
2006	118.2
2007	125.39
2008	133.37
2009	141.54
2010	150.46
2011	158.14
2012	166.59
2013	176.21
2014	186.18
2015	197.55
2016	209.06