Year	Number of
1990	169.33
1991	171.53
1992	173.02
1993	172.56
1994	172.71
1995	173.87
1996	177.51
1997	182.35
1998	188.38
1999	194.76
2000	200.87
2001	206.67
2002	213.16
2003	220.73
2004	227.98
2005	234.5
2006	240.34
2007	245.26
2008	250.22
2009	255.33
2010	261.6
2011	267.63
2012	269.88
2013	273.15
2014	276.66
2015	283.46
2016	289.2