Year	Number of
1990	30.48
1991	31.79
1992	33.19
1993	34.74
1994	36.43
1995	38.27
1996	40.75
1997	43.52
1998	46.68
1999	50.01
2000	53.46
2001	56.68
2002	59.94
2003	63.41
2004	67.18
2005	71.38
2006	74.67
2007	78.29
2008	82.19
2009	86.35
2010	90.72
2011	94.3
2012	98.08
2013	102.13
2014	106.38
2015	110.84
2016	115.26