This is one of several findings out today from a survey of 50 ad buyers that Cowen & Co says helped it to update and expand its coverage of Internet and New Media stocks. The advertisers are upbeat about 2013, seeing overall U.S. spending grow 4.6% vs 2012. That’s pretty good considering how much the election and Olympics boosted this year’s sales. But the additional dollars will mostly go to digital media — and especially those that appeal to smartphone and tablet owners. Digital will account for 33.5% of next year’s spending, up from 28.7% this year, Cowen analyst John Blackledge says. Meanwhile, TV’s market share will fall to 39.3% from 41.4%. The company notes that “TV consumption has remained static at 12-13 hrs/week” from 2004 to 2010. “Only Internet consumption has increased, from under 6 hrs/week in 2004 to 13 hrs/week in 2010.” The big surprise, though, is how eager advertisers are to spend on mobile. Cowen projects that smartphones, tablets and other portable devices will account for 26% of digital ad sales in 2018, up from 9% this year. But the firm says its survey suggests that the forecast may be too conservative — and that mobile could account for more than half of all digital ad sales in six years. That should concern moguls because Cowen says that “mobile ad dollars come at the expense of traditional ad mediums (TV, print, radio, etc).” Google is well-positioned to benefit, Blackledge says. But companies including Yahoo and AOL that depend heavily on display ads might run into trouble.