Year	Number of
1990	122.2
1991	127.49
1992	134.12
1993	141.25
1994	147.77
1995	152.87
1996	155.12
1997	155.75
1998	160.36
1999	155.46
2000	153.03
2001	149.53
2002	156.74
2003	160.86
2004	159.69
2005	166.73
2006	171.75
2007	177.33
2008	187.81
2009	191.21
2010	194.24
2011	200.5
2012	205.47
2013	209.52
2014	214.43
2015	215.29
2016	217.92