Millennial Media today released its 2012 year in review Mobile Mix Report, which showed Apple and Samsung remaining the top device manufacturers on its platform.

Apple remained the No. 1 OEM manufacturer on the mobile ad network’s platform in 2012, increasing its impressions share 5 percent year-over-year from 26 percent to 31 percent of the total impressions on Millennial Media’s top 15 device manufactures list. Samsung also maintained its No. 2 spot on the top 15 device manufactures list, thanks to a 5 percent growth in impressions since 2011 from 17 percent of total impressions on Millennial’s platform to 22 percent. The most notable newcomer to the ad network’s top 15 manufacturers list for 2012 was Amazon, landing at the No. 11.

Apple’s suite of iPhone devices — including the 4S, 5, etc. — also remained the top device on Millennial Media’s network in 2012, accounting for 15.59 percent of impressions, a 72 percent increase year-over-year. Impressions for Samsung’s flagship smartphone device, the Galaxy S, grew 182 percent in 2012, moving the device up five spots to the No. 2 position on Millennial Media’s top 20 mobile phones list. Tablet-wise, the Apple iPad stood pat as the No. 1 tablet on Millennial’s platform for 2012.

Based on ad impressions on Millennial’s network, smartphones were once again the leading device in 2012, increasing 7 percent for a 75 percent share of the total platform impressions. In second were non-phone connected devices — tablets, e-readers, etc. –, increasing 5 percent year-over-year to 20 of impressions in the ad network’s platform. Millennial Media attributed the majority of the growth of that category to the adoption rate increase of tablets. The feature phone category, as expected, fell from 17 percent in 2011 to 5 percent in 2012.

Now the breakdown for the operating systems on devices was stagnant year-over-year. Android was once again the top OS on Millennial’s platform at 48 percent, which was only a 1 percent increase since 2011. iOS was the second largest OS, with 32 percent of the impression share, down one percent year-over-year. Millennial also broke down OS share for tablets, with iOS taking a 58 percent impression share among all tablet OS. Android took a 41 percent share, with Samsung as the leading Android tablet manufacture with a 45 percent share.