Year	Number of
1990	61.61
1991	65.49
1992	69.62
1993	74.2
1994	79.1
1995	84.36
1996	91.89
1997	100.11
1998	109.31
1999	119.44
2000	130.62
2001	141.83
2002	154.25
2003	168.2
2004	183.32
2005	199.64
2006	215.1
2007	231.4
2008	248.76
2009	267.84
2010	288.99
2011	307.71
2012	328.3
2013	350.22
2014	373.39
2015	397.68
2016	424.3