Year	Number of
1990	128.49
1991	127.24
1992	125.61
1993	123.96
1994	122.72
1995	122.26
1996	123.21
1997	124.98
1998	127.49
1999	128.21
2000	128.35
2001	129.66
2002	133.91
2003	137.25
2004	140.21
2005	143.4
2006	146.88
2007	150.81
2008	154.72
2009	157.4
2010	159.74
2011	163.06
2012	169.95
2013	173.67
2014	178.04
2015	182.98
2016	189.04