Year	Number of
1990	33.75
1991	36.88
1992	40.28
1993	44.19
1994	48.51
1995	53.32
1996	58.24
1997	63.7
1998	70.01
1999	76.6
2000	83.35
2001	87.53
2002	91.63
2003	95.81
2004	100.41
2005	105.7
2006	112.99
2007	121.2
2008	130.17
2009	139.99
2010	150.65
2011	158.67
2012	167.11
2013	176
2014	185.67
2015	196.29
2016	208.19