Year	Number of
1990	182.51
1991	179.2
1992	176.34
1993	175.05
1994	176.47
1995	181.33
1996	185.02
1997	192.63
1998	201.94
1999	210.32
2000	216.69
2001	216.77
2002	214.77
2003	211.72
2004	209.41
2005	208.81
2006	212.71
2007	217.98
2008	224.38
2009	230.79
2010	236.93
2011	242.37
2012	247.46
2013	252.15
2014	257
2015	262.25
2016	268.13