Year	Number of
1990	103.26
1991	104.19
1992	105.18
1993	106.26
1994	107.27
1995	109.05
1996	108.12
1997	106.04
1998	104.8
1999	101.83
2000	102.85
2001	100.41
2002	102.05
2003	105.08
2004	110.51
2005	116.53
2006	121.11
2007	125.95
2008	131.02
2009	135.74
2010	143.91
2011	151.17
2012	158.25
2013	163.92
2014	170.45
2015	176.85
2016	183.72