Year	Number of
1990	145.35
1991	146.66
1992	148.14
1993	149.67
1994	151.55
1995	153.79
1996	158.08
1997	163.48
1998	169.66
1999	178.18
2000	187.53
2001	192.14
2002	196.94
2003	201.82
2004	206.95
2005	212.26
2006	214.36
2007	216.65
2008	219.22
2009	222.1
2010	225.53
2011	230.39
2012	235.94
2013	241.87
2014	248.4
2015	255.56
2016	262.99