Year	Number of
1990	91.66
1991	91.12
1992	90.39
1993	89.63
1994	89.08
1995	89.1
1996	90.07
1997	91.54
1998	93.43
1999	93.26
2000	92.7
2001	93.18
2002	95.98
2003	98
2004	99.67
2005	101.6
2006	104.17
2007	106.76
2008	109.39
2009	111.42
2010	113.18
2011	115.93
2012	121.27
2013	124.44
2014	127.89
2015	131.63
2016	136.17