Year	Number of
1990	43.09
1991	43.94
1992	44.96
1993	46.08
1994	47.3
1995	48.69
1996	49.79
1997	51.02
1998	52.45
1999	54.63
2000	57.11
2001	59.07
2002	61.1
2003	63.26
2004	65.63
2005	68.14
2006	71.09
2007	74.25
2008	77.74
2009	81.5
2010	85.48
2011	88.62
2012	91.96
2013	95.42
2014	99.19
2015	103.29
2016	107.43