Year	Number of
1990	71.6
1991	72.55
1992	73.66
1993	74.49
1994	75.6
1995	77.02
1996	77.62
1997	77.97
1998	78.56
1999	79.06
2000	79.51
2001	81.01
2002	82.74
2003	85.99
2004	88.8
2005	91.08
2006	93.33
2007	95.13
2008	97.28
2009	100.05
2010	103.68
2011	107.51
2012	112
2013	116.37
2014	120.85
2015	125.61
2016	130.21