Year	Number of
1990	134.38
1991	136.04
1992	140.46
1993	144.97
1994	149.02
1995	151.84
1996	158.28
1997	157.44
1998	158.47
1999	164.7
2000	167.22
2001	169.74
2002	171.29
2003	175.04
2004	176.36
2005	179.64
2006	179.64
2007	182.18
2008	184.56
2009	188.72
2010	196.4
2011	205.49
2012	212.6
2013	218.97
2014	224.57
2015	234.53
2016	243.79