Year	Number of
1990	93.22
1991	99.55
1992	106.4
1993	113.76
1994	121.65
1995	130.12
1996	135.02
1997	140
1998	144.89
1999	149.77
2000	154.66
2001	158.13
2002	161.35
2003	164.44
2004	167.56
2005	170.94
2006	174.27
2007	177.69
2008	181.56
2009	185.62
2010	189.9
2011	194.83
2012	199.95
2013	205.18
2014	210.63
2015	216.33
2016	222.65