Year	Number of
1990	201.46
1991	206.59
1992	211.57
1993	217.16
1994	224.78
1995	234.32
1996	240.02
1997	246.7
1998	256.24
1999	264.39
2000	269.09
2001	273.34
2002	281.47
2003	292.72
2004	306.76
2005	314.39
2006	322.75
2007	330.68
2008	341.25
2009	355.06
2010	368.63
2011	376.42
2012	384.81
2013	395.33
2014	411.93
2015	433.8
2016	451.73