Netflix is more than doubling its advertising footprint, making its ad tier available in 15 additional countries, and announcing 250 million monthly active viewers. Along with the dozen existing territories (including the U.S. and the UK and Europe), the ad tier will now be in countries like Sweden, Colombia, Thailand and New Zealand. Amy Reinhard, president of advertising at Netflix, made the announcement at the company’s upfront in New York, adding that 60% of total sign-ups now opting for ads. More than 80% of viewers of the ad tier sign in weekly. “Our viewers are super engaged, and that engagement turns into real attention for you,” Reinhard told advertisers at the event at Pier 94 Studios. “Our audience is also unique – 44% of people who see an ad on Netflix never see it on broadcast TV or other screens. In a lot of cases, they’re not even watching other streamers.…