(Courtesy photo)Key Points Ad-supported subscription streaming tiers are becoming the dominant monetization model in North America, according to new data from Ampere Analysis. The firm expects ad tiers to account for 54 percent of total subscription streaming revenue in the region by the end of the year. Subscription streaming advertising revenue alone is expected to exceed $18 billion in North America this year. North America accounts for nearly 60 percent of global ad-supported subscription streaming revenue. Ad-supported tiers are becoming the dominant business model for subscription streaming services in North America, according to new research from Ampere Analysis.