The fog surrounding the viewership for Netflix's original series is starting to thin. As more and more third-party groups try to game the secretive streamer's audiences, Nielsen Media has shared its first findings about one Netflix's most popular shows.

Orange Is the New Black, which returned for its fourth season at the stroke of midnight on June 17, was watched by 6.7 million viewers during its opening weekend, per Nielsen. The number, not confirmed by Netflix, was shared during a presentation at Nielsen's Consumer 360 conference in Las Vegas, as first reported by The Wall Street Journal.

It's a strong number for OITNB. The most recent stat about the show, which came from tech firm Symphony and NBC, was a delayed tally from well into the third season's run.

The three-day window of measurement puts it just short of Nielsen's live-plus-three-day ratings, one of the more frequently shared statistics among cable networks. For the week of OITNB's premiere, the show ranks especially competitive among cable dramas. The 6.7 million figure puts it between HBO's Game of Thrones (10.4 million) and TNT's Rizzoli & Isles (5.8 million viewers) on the cable landscape — and that's before the additional day of views in the latter's total.

Nielsen's access to the numbers is thanks to OITNB producers Lionsgate. All studios with streaming originals were given the chance to opt-in to Nielsen's new streaming measurements, which allow the company to track viewership with codes in the programming.

Netflix certainly has the reach. 58 percent of the streamer's 81.5 million subscribers are in the U.S. Nielsen also estimates that 52 percent of American households now have some form of streaming subscription, an increase of 40 percent from just two years ago.

What trade secrets remain for Netflix and other streamers ratings — and a great deal do — may soon succumb to transparency as more and more research outfits try to game the system. A quorum of TV research executives talked about the inevitability of transparency earlier this year.