Year	Number of
1990	109.05
1991	106.22
1992	100.35
1993	93.47
1994	87.7
1995	84.04
1996	89.05
1997	96.58
1998	107.97
1999	117.44
2000	126.34
2001	132.52
2002	139.89
2003	144.78
2004	150.86
2005	156.44
2006	164.84
2007	171.61
2008	177.15
2009	182.96
2010	188.74
2011	194.5
2012	201.12
2013	209.36
2014	218.44
2015	228.18
2016	237.59