Year	Number of
1990	152.3
1991	152.41
1992	150.89
1993	145.4
1994	139.77
1995	130.27
1996	124.75
1997	124.4
1998	126.08
1999	125.68
2000	121.33
2001	120.64
2002	118.85
2003	121.58
2004	126.21
2005	111.51
2006	99.56
2007	105.48
2008	115.19
2009	126.52
2010	129.78
2011	134.45
2012	142.43
2013	143
2014	150.24
2015	144.33
2016	142.24