Year	Number of
1990	148.05
1991	149.81
1992	151.05
1993	152.09
1994	153.41
1995	155.35
1996	156.06
1997	156.48
1998	156.89
1999	157.78
2000	157.41
2001	157.29
2002	158.7
2003	159.63
2004	160.65
2005	162.82
2006	163.91
2007	164.81
2008	166.14
2009	167.92
2010	170.28
2011	173.65
2012	176.82
2013	180.67
2014	185.74
2015	190.26
2016	194.79