Smartphones and tablets accounted for almost a fifth (18%) of total US search spend in Q4 2012, according to data from IgnitionOne.

Year-on-year figures show that paid search spend on tablets has increased by 163% compared to 87% on smartphones, while clicks have increased by 135% and 29% respectively.

The report also found that CPCs have increased by 45% on smartphones, while tablet CPCs have increased by a relatively low 12%. On tablets search ad impressions increased 212% while on smartphones the increase was 20%.

Separate figures published by the IAB in October show that mobile advertising accounts for 7% of all digital ad spend in the UK. So though the reports focus on different markets, it still suggests that mobile search is outperforming other areas of mobile marketing.

Looking at how mobile ad spend breaks down; display, video, SMS and MMS advertising increased like-for-like by 91% to £49.9m while mobile search grew by 152% to £131.6m – accounting for 72% of mobile ad spend.

IgnitionOne’s report states that overall paid search spend increased by 19% in Q4 YoY, with November driving much of the spend growth compared to December in 2011. Compared to Q4 2011 there were also increases in impressions (up 19%) and clicks (6%).

In terms of market share, the Yahoo Bing Network accounted for 24% of US search spend, it’s biggest share since Q1 2009, compared to 76% for Google. The former achieved a 48% increase in spend year-on-year compared to Google’s 12%, though that’s obviously from a much smaller base.

Quarterly percentage of advertising spend by engine

The report also focuses on the retail industry, revealing that search spend increased by 7% YoY. Retail search also saw above average YoY increases for impressions (28%) and clicks (10%).

IgnitionOne’s data comes from more than 94bn impressions and more than 2.5bn clicks on Google and Yahoo/Bing search networks, Google AdEx, and other display networks from January 1 2006 through to December 31 2012.