Year	Number of
1990	12.98
1991	13.67
1992	14.52
1993	15.47
1994	16.42
1995	17.27
1996	18.52
1997	19.6
1998	20.55
1999	21.52
2000	22.62
2001	24.28
2002	26.39
2003	28.97
2004	31.88
2005	35.1
2006	38.33
2007	41.82
2008	46.46
2009	52.87
2010	61.9
2011	69.69
2012	80.85
2013	94.78
2014	110.15
2015	126.01
2016	145.78