Year	Number of
1990	111.1
1991	114.51
1992	118.48
1993	123.14
1994	128.04
1995	133.37
1996	139.24
1997	145.28
1998	151.63
1999	156.5
2000	166.61
2001	164.12
2002	164.03
2003	167.48
2004	167.51
2005	170.38
2006	179.07
2007	192.72
2008	211.27
2009	229.94
2010	251.07
2011	255.19
2012	256.13
2013	255.03
2014	255.05
2015	258.33
2016	262.6