Year	Number of
1990	111.69
1991	112.75
1992	113.4
1993	113.96
1994	115.73
1995	118.84
1996	123.91
1997	130.34
1998	137.32
1999	144.8
2000	153.57
2001	159.96
2002	164.77
2003	171.9
2004	178.67
2005	185.63
2006	192.54
2007	199.53
2008	204.79
2009	210.02
2010	215.15
2011	219.38
2012	222.68
2013	226.45
2014	226.62
2015	226.98
2016	227.67