Year	Number of
1990	63.85
1991	63.92
1992	63.97
1993	66.75
1994	72.46
1995	76.22
1996	80.43
1997	82.13
1998	81.77
1999	83.55
2000	83.58
2001	81.72
2002	80.75
2003	83.61
2004	86.63
2005	90.23
2006	92.51
2007	95.48
2008	98.62
2009	100.03
2010	102.86
2011	104.59
2012	106.67
2013	109.61
2014	112.53
2015	116.1
2016	119.6