Year	Number of
1990	127.35
1991	126.26
1992	128.61
1993	131
1994	135.25
1995	138.43
1996	139.86
1997	139.15
1998	138.18
1999	139.5
2000	144.69
2001	148.06
2002	153.71
2003	156.58
2004	162.11
2005	167.2
2006	171.69
2007	180.36
2008	186.1
2009	195.05
2010	202.77
2011	207.35
2012	213.21
2013	220.24
2014	228.17
2015	236.66
2016	246.74