Year	Number of
1990	135.76
1991	138.52
1992	141.86
1993	146.76
1994	150.25
1995	154.4
1996	157.05
1997	162.11
1998	167.98
1999	169.78
2000	174.85
2001	175.01
2002	177.39
2003	181.54
2004	186.2
2005	191.37
2006	196.98
2007	203.93
2008	210.65
2009	217.47
2010	228.97
2011	237.44
2012	252.39
2013	265.53
2014	276.87
2015	287.79
2016	301.75