Year	Number of
1990	174.69
1991	175.85
1992	177.71
1993	178.89
1994	181.78
1995	185.85
1996	189.07
1997	192.16
1998	196.97
1999	197.71
2000	199.46
2001	201.67
2002	203.67
2003	206.81
2004	208.23
2005	213.27
2006	218.28
2007	223.5
2008	226.83
2009	230.86
2010	236.32
2011	241.76
2012	248.22
2013	256.17
2014	263.19
2015	269.5
2016	276.31