Year	Number of
1990	77.2
1991	77.6
1992	78.92
1993	80.26
1994	82.05
1995	84.28
1996	87.73
1997	90.26
1998	95.92
1999	101.27
2000	105.72
2001	106.86
2002	108.86
2003	114.15
2004	120.25
2005	126.77
2006	134.11
2007	141.01
2008	147.45
2009	154.62
2010	161.37
2011	168.28
2012	179.02
2013	190.34
2014	202.62
2015	214.74
2016	225.94