Year	Number of
1990	71.33
1991	74.18
1992	77.31
1993	80.96
1994	85.19
1995	90.23
1996	94.95
1997	100.1
1998	110.29
1999	119.5
2000	127.08
2001	133.22
2002	139.25
2003	151.19
2004	161.67
2005	171.44
2006	179.56
2007	187.47
2008	198.76
2009	211.11
2010	226.35
2011	242.51
2012	257.91
2013	277.18
2014	298.58
2015	314.56
2016	332.14