Year	Number of
1990	20.77
1991	22.45
1992	24.65
1993	27.24
1994	30.14
1995	33.27
1996	33.2
1997	32.64
1998	31.84
1999	31.16
2000	30.55
2001	31.85
2002	33.62
2003	35.52
2004	37.39
2005	39.67
2006	41.81
2007	43.73
2008	47.87
2009	54.65
2010	63.89
2011	71.07
2012	81.23
2013	94.74
2014	110.08
2015	126.83
2016	147.48