An increased number of publishers are using header bidding in 2017 to get the most out of their programmatic inventory, according to a new review of trillions of impressions moving through global programmatic inventory.

Sell-side platform PubMatic’s annual review of its global traffic, which it says gets “tens of trillions” of impressions every month, suggests mobile header bidding in particular became more popular last year with a 244% increase in monetized impression volume growth over 2016. Desktop volume increased 148%.

Header bidding describes technology that allows a publisher to offer programmatic inventory to select exchanges before calling out to big ad servers, such as those run by Google. The practice is typically undertaken in the belief that it gets better rates for publishers.

The annual report also noted a global uptick in private marketplace (PMP) use. While Canada has typically seen relatively high adoption of PMPs, global markets seem to be following suit as issues of brand safety and inventory quality become more prominent. PMP impression volume in mobile apps increased 85% over 2017, compared to a 50% increase on the mobile web and a 15% increase on desktop inventory.