The market for web TV streaming devices is heating up and Roku and Google’s Chromecast look like the big winners so far. Per GigaOM, new data from researchers at Parks Associates estimates that both Chromecast and Roku each have sold around 3.8 million units in the United States over the past year while Apple TV has sold only 2 million units in the U.S. over the same period. This makes a lot of sense because Chromecast and Roku’s new USB dongle are both less expensive than Apple TV, which is supposedly due for a major refresh sometime this year.

Even so, Apple has still has cumulatively sold 20 million Apple TV units worldwide since its launch seven years ago while Roku is still at 8 million units sold total. We expect that to change as Roku becomes available in more markets, however, as GigaOM points out that right now that it’s limited to the U.S., Canada, the U.K. and Ireland.