Global smartphone ad impressions on the InMobi network increased 488% in Q4 2011 compared to Q4 2010.

The figures, released today in the InMobi Mobile Market 2011 Review, also show that mobile impressions grew 251% in the same period.

Tablet impressions experienced massive growth year-on-year, increasing 771% to 11.2bn.

While the top handset for ad impressions was the iPhone 4, the Android OS has the largest share of impressions overall with 13.4% compared to Apple’s 9.7%

InMobi’s findings show that mobile advertising is becoming increasingly important. Data included in Econsultancy’s Internet Statistics Compendium reveals that mobile ad spending in EMEA will reach $2bn by 2015, putting it on par with North America.

Here is the infographic, the data is sourced from InMobi’s global mobile advertising network, which served over 200bn impressions in Q4 2011.