Year	Number of
1990	24.81
1991	26.05
1992	27.42
1993	28.73
1994	30.22
1995	31.95
1996	33.81
1997	35.87
1998	37.91
1999	39.99
2000	42.34
2001	44.32
2002	46.76
2003	49.97
2004	55.51
2005	64.37
2006	72.54
2007	84
2008	96.37
2009	110.94
2010	124.34
2011	140.2
2012	154.13
2013	167.04
2014	179.91
2015	194.09
2016	211.05