35% rise in ad spend by prez hopefuls since 2012

Over half a billion dollars have been spent on TV ads by presidential hopefuls in the US election campaign, zapping people's minds with over 600,000 airings since the start of the primaries last year. This barrage has meant an unprecedented 35% increase in ad-spend compared to the same point in the 2012 election.
This spectacular level of the usual ad-war is all the more astonishing because one of the Republican candidates, Donald Trump, had not spent anything on TV ads.The airwaves were hogged by his bitter rivals who fell by the side as the primaries progressed. Democrat Hillary Clinton has largely outspent her rivals by a big margin. These figures emerge from an analysis done by the Wesleyan Media Project of TV ads data tracking done by Kantar MediaCMAG. It co vers all broadcast TV ads but does not include cable ads placed locally.
TV ad campaigning is a staple of US elections and millions are spent on it. A study by MIT's Poverty Action Lab in 2006 had shown that such ads can cause significant shifts in support but the effect doesn't last more than a week.
How are the two rivals, Hillary Clinton and Trump, handling the TV ad campaign after they won the primaries? Wesleyan's analysis shows that after June 8 , when all primaries were done and dusted with, Clinton or her supporting groups had bought $88 million worth of TV ad slots while Trump's supporters had managed just $9 million worth.
Green Party candidate Jill Stein had aired only 38 ads, while Purple PAC, which supports Libertarian Party nominee Gary Johnson, has aired only two ads. “We haven't seen a modern presidential campaign that is so lopsided in terms of adverti sing,“ said Erika Franklin Fowler, co-director of the Wesleyan Media Project. “It's tough to parse out advertising's contribution to Clinton's current lead in polls relative to other factors, but there is little doubt that Trump could use more disciplined messaging on air.“
The Trump campaign bought its first TV ad on August 19 in some states. Between 19th and 21st August, the Clinton campaign had 2,746 ads while Trump had fielded 1,275.
The analysis shows that only about a third of the ads were positive, that is, they talked about the favoured candidate and hisher qualities, half were `negative', featuring attacks on opponents while 20% of the ads contrasted the two candidates.
Clinton is well ahead of Trump in the overall fund raising race also. She netted $61 million between July 21 and August 21 while Trump managed only 38 million according to Centre for Responsive Politics analysis of federal filings.