Year	Number of
1990	143.68
1991	139.12
1992	133.84
1993	127.4
1994	120.04
1995	116.85
1996	111.95
1997	113.52
1998	108.88
1999	109.58
2000	110.75
2001	116.06
2002	124.02
2003	130.52
2004	134.72
2005	141.4
2006	145.22
2007	148.48
2008	151.05
2009	151.85
2010	152.96
2011	155.05
2012	155.6
2013	155.82
2014	156.64
2015	159.5
2016	163.77