Year	Number of
1990	27.45
1991	28.4
1992	29.49
1993	30.62
1994	31.8
1995	32.97
1996	34.32
1997	35.69
1998	37.21
1999	38.88
2000	40.74
2001	43.93
2002	47.4
2003	51.24
2004	55.54
2005	60.47
2006	63.99
2007	67.86
2008	72.24
2009	76.96
2010	81.99
2011	87.31
2012	92.89
2013	98.78
2014	104.98
2015	111.58
2016	119.06