Year	Number of
1990	126.6
1991	130.35
1992	134.42
1993	138.77
1994	143.31
1995	148.09
1996	150.39
1997	152.73
1998	154.86
1999	156.13
2000	157.8
2001	158.2
2002	158.86
2003	160.11
2004	161.87
2005	164.17
2006	166.16
2007	168.53
2008	171.42
2009	174.79
2010	178.64
2011	183.63
2012	189.57
2013	195.95
2014	202.81
2015	210.06
2016	217.68