The mobile ad-serving startup platform MoPub reported today that 75 percent of mobile advertising dollars in the U.S., Europe, Asia and Latin America were spent on iOS devices, as my colleague Erica Ogg reports today. The iPad accounted for about 20 percent of all mobile ad spending, while Android tablets claimed less than 1 percent.

MoPub’s figures mirror data released earlier this week from Opera (and reported by TechCrunch), which indicated Android tablets claimed a mere .49 percent of overall mobile advertising revenues during the first quarter even though they drove more than 1 percent of all mobile ad traffic. The iPad, conversely, claimed 12.6 percent of all mobile ad revenues but generated only 6.54 percent of all mobile ad traffic.

All those figures are noteworthy because Android tablets are quickly closing the gap with the iPad in terms of device market share, and they may overtake overall iPad sales this year. Ad revenues on Android tablets are sure to rise as Apple’s dominance wanes, but for mobile web and app publishers the iPad is clearly where the ad money is today.