Year	Number of
1990	63.9
1991	68.62
1992	74.1
1993	79.4
1994	85.05
1995	91.5
1996	97.38
1997	107.81
1998	120.26
1999	128.88
2000	140.54
2001	147.15
2002	156.79
2003	164.91
2004	177.55
2005	186.95
2006	196.53
2007	203.06
2008	206.65
2009	219.37
2010	228.19
2011	242.26
2012	250.5
2013	254.78
2014	267.05
2015	274.43
2016	283.77