Year	Number of
1990	146.59
1991	153.11
1992	159.73
1993	166.88
1994	174.24
1995	181.91
1996	191.1
1997	200.72
1998	210.88
1999	221.38
2000	232.3
2001	243.01
2002	254.01
2003	265.6
2004	277.72
2005	290.5
2006	307.28
2007	325.14
2008	344.57
2009	365.12
2010	386.85
2011	408.23
2012	430.78
2013	454.53
2014	479.73
2015	506.58
2016	535.65