Year	Number of
1990	138.45
1991	133.45
1992	134.61
1993	136.36
1994	137.36
1995	141.58
1996	142.55
1997	146.49
1998	152.12
1999	159.5
2000	166.53
2001	177.28
2002	184.62
2003	196.65
2004	206.88
2005	220.21
2006	235.16
2007	249.23
2008	263.67
2009	281.34
2010	300.91
2011	314.92
2012	329.47
2013	345
2014	360.76
2015	376.73
2016	391.84