Year	Number of
1990	141.12
1991	142.61
1992	144.06
1993	145.58
1994	147.19
1995	148.45
1996	149.75
1997	151.33
1998	153.05
1999	152.59
2000	154.13
2001	156.95
2002	156
2003	158.4
2004	159.97
2005	162.64
2006	165.29
2007	167.34
2008	168.53
2009	171.34
2010	172.28
2011	172.32
2012	174.31
2013	176.24
2014	177.9
2015	179.69
2016	182.48