Year	Number of
1990	140.54
1991	143.39
1992	146.53
1993	149.82
1994	153.02
1995	156.19
1996	159.03
1997	157.79
1998	156.88
1999	153.19
2000	150.15
2001	142.95
2002	137.89
2003	134.83
2004	133.28
2005	131.62
2006	128.52
2007	125.53
2008	124.12
2009	124.6
2010	126.49
2011	128.41
2012	130.74
2013	133.46
2014	136.41
2015	140.05
2016	144.18