Year	Number of
1990	62.47
1991	64.6
1992	67.25
1993	69.74
1994	72.53
1995	75.61
1996	76.76
1997	78.95
1998	81.22
1999	83.97
2000	87.15
2001	90.55
2002	93.33
2003	96.32
2004	99.8
2005	103.72
2006	109.07
2007	113.34
2008	118.43
2009	123.47
2010	128.81
2011	132.32
2012	136.15
2013	140.77
2014	145.47
2015	150.24
2016	154.7