Year	Number of
1990	137.12
1991	140.13
1992	143.78
1993	148.05
1994	152.68
1995	157.76
1996	161.14
1997	164.91
1998	168.86
1999	173.27
2000	178.31
2001	182.2
2002	186.76
2003	191.48
2004	196.45
2005	201.74
2006	205.25
2007	208.57
2008	212.54
2009	217.2
2010	222.9
2011	227.81
2012	233.99
2013	241.09
2014	248.7
2015	256.56
2016	264.67