Year	Number of
1990	41.93
1991	42.32
1992	43.1
1993	44.02
1994	44.96
1995	45.83
1996	46.16
1997	46.42
1998	46.93
1999	47.87
2000	49.47
2001	51.54
2002	54.44
2003	57.96
2004	61.51
2005	64.89
2006	68.39
2007	71.55
2008	75.02
2009	79.41
2010	85.29
2011	89.58
2012	95.16
2013	101.38
2014	107.12
2015	111.79
2016	117.11