Netflix may never fully quantify its viewership for different series, but it’s a fair bet that Stranger Things marks one of their biggest successes. So much so, in fact, that Nielsen ratings have produced data claiming that Season 2 earned upwards of fifteen million views for its premiere, and impressive numbers for all nine episodes.

Keep in mind that Netflix itself never condones any outside group attempting to measure its “ratings,” but the famed Nielsen group has now turned its sights on Netflix with a look at “audio codes within programming.” The data doesn’t take into account mobile Netflix streaming, but the numbers claim 15.8 million viewers watched the Stranger Things 2 premiere within three days of its launch, with four million finishing the season altogether.

Here’s how The Hollywood Reporter breaks it down:

“Chapter Two” — 13.7 million viewers; 9.6 million people 18-49
“Chapter Three” — 11.6 million viewers; 8.1 million viewers 18-49
“Chapter Four” — 9.3 million viewers; 6.6 million viewers 18-49
“Chapter Five” — 8 million viewers; 5.6 million viewers 18-49
“Chapter Six” — 6.4 million viewers; 4.5 million viewers 18-49
“Chapter Seven” — 5.3 million viewers; 3.7 million viewers 18-49
“Chapter Eight” — 4.9 million viewers; 3.4 million viewers 18-49
“Chapter Nine” — 4.6 million viewers; 3.2 million viewers 18-49

A total of 361,000 also finished Season 2 within the first twenty-four hours, which could place the series higher on Netflix’s own “Binge-Racers” list. It’s believed that more firm viewership data could impact talent contracts, as well as library deals for existing series that attract more streams.

We’ll see if Netflix steps up to corroborate or debunk Nielsen’s report, but might such significant ratings convince the Duffers to rethink Stranger Thingsfive-season plan?

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