Year	Number of
1990	74.57
1991	74.48
1992	73.76
1993	73.39
1994	73.46
1995	71.92
1996	70.97
1997	72.55
1998	72.97
1999	73.57
2000	76.18
2001	78.29
2002	81.16
2003	84.76
2004	84.95
2005	88.58
2006	89.8
2007	94.98
2008	97.82
2009	99.98
2010	102.91
2011	106.27
2012	109.62
2013	113.63
2014	117.37
2015	120.53
2016	124.45