Paul, there is ten TB of data a DAY uploaded to usenet. According to
http://www.morganelligroup.com/usenet-stats/
Daily Volume Date Source
4.5 GB 1996-12 Altopia.com
9 GB 1997-07 Altopia.com
12 GB 1998-01 Altopia.com
26 GB 1999-01 Altopia.com
82 GB 2000-01 Altopia.com
181 GB 2001-01 Altopia.com
257 GB 2002-01 Altopia.com
492 GB 2003-01 Altopia.com
969 GB 2004-01 Altopia.com
1.30 TB 2004-09-30 Octanews.net
1.38 TB 2004-12-31 Octanews.net
1.52 TB 2005-01 Altopia.com
1.34 TB 2005-01-01 Octanews.net
1.30 TB 2005-01-01 Newsreader.com
1.81 TB 2005-02-28 Octanews.net
1.87 TB 2005-03-08 Newsreader.com
2.00 TB 2005-03-11 Various sources
2.27 TB 2006-01 Altopia.com
2.95 TB 2007-01 Altopia.com
3.07 TB 2008-01 Altopia.com
3.80 TB 2008-04-16 Newsdemon.com
4.60 TB 2008-11-01 Giganews.com
4.65 TB 2009-01 Altopia.com
6.00 TB 2009-12 Newsdemon.com
5.42 TB 2010-01 Altopia.com
8.00 TB 2010-09 Newsdemon.com
7.52 TB 2011-01 Altopia.com
8.25 TB 2011-10 Thecubenet.com
9.19 TB (estimate) 2012-01 Altopia.com
Hope that helps to give you an idea of the scale.