The half-yearly BTA observation reports
(PowerPoint)

 2002 

I half-year

II half-year

 2003 

I half-year

II half-year

 2004 

I half-year

II half-year

 2005 

I half-year

II half-year

 2006 

I half-year

II half-year

 2007 

I half-year

II half-year

 2008 

I half-year

II half-year

 2009 

I half-year

II half-year

 2010 

I half-year

II half-year

 2011 

I half-year

II half-year

 2012 

I half-year

II half-year

 2013 

I half-year

II half-year

 2014 

I half-year (pdf)

II half-year (pdf)

 2015 

I half-year