The season 2 premiere episode of “13 Reasons Why,” Netflix’s controversial teen-suicide drama series, averaged 6.08 million viewers in the U.S. in the first three days of its release, according to Nielsen estimates.

That’s less than half the number of viewers who watched the first episode of “Stranger Things” season 2 — which averaged 15.8 million — in the first three days of its release last fall, according to Nielsen. Around 11 million U.S. viewers watched Netflix’s fantasy-cop movie “Bright” starring Will Smith during its first three days of release last December, according to Nielsen. “Stranger Things” S2 remains the most-watched Netflix original over the initial three-day window since Nielsen began tracking the subscription VOD space in mid-2017.

Netflix released “13 Reasons Why” season 2 on May 18. The show follows the events in the aftermath of a high-school girl’s suicide, revolving around a lawsuit her parents have filed against the school.

The show’s audience skews heavily toward young and female viewers, according to Nielsen. According to the initial data, “13 Reasons Why” season 2 has had virtually the same gender split of Netflix’s “The Crown” (65% female, 35% male) but it had almost the opposite age distribution. About 75% of the viewers for “13 Reasons Why” were 34 or younger while 75% of “The Crown’s” audience was aged 35 or older.

Overall, within the first three days of its availability (May 18-20), “13 Reasons Why” season 2 garnered an average minute audience of over 2.6 million U.S. viewers across all 13 episodes, per Nielsen. Netflix U.S. members who streamed “13 Reasons Why” season 2 watched an average of more than four episodes over the initial three-day period, Nielsen found.

Netflix doesn’t release viewing metrics — it doesn’t have to, because it doesn’t run ads — and the company’s execs have discounted third-party attempts to measure viewership.

It’s worth noting that Nielsen’s estimates cover only the U.S. and tracks viewership only on internet-connected TVs (excluding mobile devices and computers). The Nielsen SVOD Content Ratings, launched last fall, extrapolate viewership using audio-recognition technology that “listens” to what viewers are watching on TV.

Ted Sarandos, Netflix’s chief content officer, has said the company’s originals don’t need to generate a big initial audience (in the way TV networks do) to be cost-efficient investments over a longer period. “We have many shows that don’t work the first weekend, or first week, or first month,” he said, speaking Tuesday at the Paley Center for Media in New York. But over time, “they grow and grow and grow.”