Year	Number of
1990	50.92
1991	52.16
1992	55.04
1993	56.14
1994	58.16
1995	60.93
1996	65.05
1997	70.48
1998	76.03
1999	80.21
2000	84.71
2001	87.76
2002	91.81
2003	94.24
2004	97.65
2005	103
2006	107.52
2007	112.77
2008	116.06
2009	118.22
2010	121.68
2011	127.02
2012	133
2013	138.19
2014	139.48
2015	143.97
2016	144.94