Year	Number of
1990	103.44
1991	106.6
1992	109.98
1993	113.86
1994	117.97
1995	122.33
1996	126.99
1997	131.86
1998	137.26
1999	143
2000	149.14
2001	155.39
2002	162.14
2003	169.6
2004	177.48
2005	185.77
2006	196.84
2007	208.47
2008	221.11
2009	234.63
2010	249.17
2011	266.26
2012	284.74
2013	304.9
2014	326.56
2015	349.79
2016	374.52