Year	Number of
1990	170.82
1991	173.15
1992	171.93
1993	186.91
1994	191.55
1995	194.64
1996	201.06
1997	203.5
1998	209.09
1999	214.88
2000	217.15
2001	220.02
2002	225.39
2003	229.11
2004	232.67
2005	237.11
2006	241.69
2007	244
2008	246
2009	250.63
2010	260.37
2011	266.06
2012	268.74
2013	276.51
2014	282.29
2015	290.13
2016	296.74