Year	Number of
1990	57.01
1991	61.65
1992	65.17
1993	68.73
1994	72.98
1995	77.04
1996	81.77
1997	86.31
1998	90.42
1999	93.34
2000	96.56
2001	99.94
2002	103.17
2003	105.89
2004	108.46
2005	111.75
2006	115.62
2007	119.03
2008	122.16
2009	124.58
2010	128.97
2011	132.33
2012	135.69
2013	141.42
2014	143.65
2015	146.03
2016	148.9