Year	Number of
1990	87.53
1991	91.65
1992	96.05
1993	100.66
1994	105.52
1995	110.67
1996	114.21
1997	117.8
1998	121.26
1999	124.77
2000	128.39
2001	130.65
2002	132.82
2003	135.02
2004	137.31
2005	139.82
2006	142.08
2007	144.44
2008	147.21
2009	150.17
2010	153.38
2011	157.35
2012	161.54
2013	165.9
2014	170.5
2015	175.38
2016	180.89