Year	Number of
1990	1322.37
1991	1302.13
1992	1312.81
1993	1295.27
1994	1304.69
1995	1286.21
1996	1271.4
1997	1263.55
1998	1255.66
1999	1233.6
2000	1239.01
2001	1235.93
2002	1237.96
2003	1239.63
2004	1244.28
2005	1262.45
2006	1258.5
2007	1241.83
2008	1214.95
2009	1178.59
2010	1146.84
2011	1116.97
2012	1096.96
2013	1079.25
2014	1067.05
2015	1059.39
2016	1054.42