Year	Number of
1990	107.47
1991	110.05
1992	117.12
1993	123.28
1994	131.17
1995	137.32
1996	140.54
1997	141.64
1998	145.17
1999	149.76
2000	149.91
2001	152.91
2002	156.06
2003	160.02
2004	166.4
2005	173.68
2006	182.28
2007	190.46
2008	197.89
2009	208.88
2010	222.83
2011	234.54
2012	245.1
2013	253.67
2014	258.6
2015	254.24
2016	253.05