http://googleenterprise.blogspot.com/2009/03/spam-data-and-trends-q1-2009.html -- perl -ple 's:20(\d\d)([01]\d)([0123]\d):qw/fri sat sun mon tue wed thu/[($1*1.25+$3+(1,4,4,0,2,5,0,3,6,1,4,6)[$2-1])%7]:e'