Year	Number of
1990	60.35
1991	62.65
1992	65.08
1993	67.77
1994	70.51
1995	73.45
1996	75.24
1997	77.4
1998	79.52
1999	81.83
2000	83.91
2001	85.63
2002	87.25
2003	89.01
2004	90.93
2005	92.61
2006	94.91
2007	97.63
2008	100.09
2009	102.16
2010	103.87
2011	106.77
2012	110.22
2013	112.97
2014	115.84
2015	119.62
2016	123.91