Year	Number of
1990	115.91
1991	114.42
1992	112.7
1993	111.05
1994	109.89
1995	109.51
1996	110.42
1997	112.32
1998	114.98
1999	117.87
2000	120.92
2001	123.04
2002	125.42
2003	127.92
2004	130.49
2005	133.24
2006	135.89
2007	138.35
2008	140.91
2009	143.64
2010	146.72
2011	149.31
2012	152.35
2013	155.6
2014	159.15
2015	162.99
2016	167.85