1995,5.885562,
1996,4.39123,
1997,5.184548,
1998,7.968137,
1999,6.877479,
2000,6.892842,
2001,5.984192,
2002,6.545753,
2003,5.669699,
2004,5.967869,
2005,7.350274,
2006,7.756164,
2007,6.577918,
2008,6.282923,
2009,5.705178,
2010,7.745452,
2011,6.819918,
2012,8.393661,
2013,6.401151,
2014,4.856795,
2015,6.210521,
2016,8.039891,
2017,6.918877,