Year	Number of
1990	161.02
1991	163.75
1992	166.94
1993	170
1994	173.43
1995	177.23
1996	181.98
1997	187.11
1998	192.19
1999	197.48
2000	203
2001	207.01
2002	211.27
2003	216.5
2004	221.73
2005	226.95
2006	230.07
2007	233.32
2008	237.01
2009	241.14
2010	245.81
2011	249.42
2012	253.52
2013	257.82
2014	262.14
2015	266.38
2016	270.72