Year	Number of
1990	178.42
1991	175.58
1992	178.88
1993	180.1
1994	182.9
1995	190.78
1996	197.21
1997	204.58
1998	213.15
1999	216.17
2000	218.82
2001	221.96
2002	225.33
2003	229.74
2004	233.79
2005	237.42
2006	241.24
2007	244.58
2008	248.72
2009	253.61
2010	258.56
2011	263.4
2012	268.28
2013	273.82
2014	279.68
2015	285.8
2016	292.13