U.S. networks pumped out <A HREF="http://news.zdnet.com/2100-1009_22-6168456.html?tag=nl.r23660">the highest percentage of attacks</A> during the second half of last year, with China running a distant second, according to a report released by Symantec.

The U.S. accounted for 31 percent of malicious activity originating from computer networks, while 10 percent came from China and 7 percent from Germany, Symantec said in its Internet Security Threat Report.