Year	Number of
1990	140.19
1991	136.31
1992	133.52
1993	136.71
1994	136.69
1995	140.15
1996	138.52
1997	136.73
1998	136.98
1999	135.31
2000	136.91
2001	131.34
2002	129.99
2003	127.72
2004	130.11
2005	132.9
2006	131.21
2007	130.34
2008	129.63
2009	133.09
2010	134.14
2011	137.32
2012	135.98
2013	138.69
2014	139.5
2015	142.37
2016	144.59