Year	Number of
1990	80.11
1991	79.47
1992	78.65
1993	77.84
1994	77.29
1995	77.19
1996	78.06
1997	79.45
1998	81.3
1999	82.59
2000	84.11
2001	84.97
2002	86.27
2003	87.59
2004	89.03
2005	90.53
2006	92.35
2007	94.03
2008	95.8
2009	97.86
2010	100.16
2011	102.29
2012	104.69
2013	107.17
2014	109.86
2015	112.72
2016	116.18