Story highlights At least 10.2 million viewers tune in Sunday to season 4 premiere

That's up from 7.9 million at the start of "Downton's" season three

PBS executive says the show has become a post-holiday tradition

The "Downton Abbey" phenomenon just keeps getting bigger.

Sunday's season four premiere of the upstairs-downstairs drama on PBS surpassed the comparable ratings for every previous episode. According to Nielsen data, at least 10.2 million viewers tuned in live (or within a few hours via digital video recorders) on Sunday night, up from 7.9 million at the start of season three and 8.2 million at the end of it.

This was more than a "personal best" for "Downton." The season four premiere outperformed every other drama on Sunday night, too. CBS's "The Good Wife," for instance, had 9.2 million viewers; ABC's "Revenge" had 6.7 million. (All these totals will increase once several days of digital video recorder viewership is factored in.)

PBS isn't rated like a traditional network because it doesn't carry traditional commercials.

But even last season's "Downton" premiere was described as one of the highest-rated events in the history of the public broadcasting network; analysts said PBS hadn't seen numbers this high since the premiere of the "Civil War" documentary series in 1990. An apples-to-apples comparison is impossible because of changes in ratings methodology. But the season four premiere affirms that "Downton" is making history for the network.

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Season four, of course, debuted several months ago in the United Kingdom. PBS has received no small amount of criticism for its decision to delay the episodes in the United States, and the network's executives are aware that some fans get a sneak peek by finding the episodes illegally on the Internet. But they say the sky-high ratings two seasons in a row are proof that their scheduling strategy is a wise one.

Paula Kerger, the chief executive of PBS, said in a statement on Monday, "I'm so pleased that millions of viewers have returned to 'Downton Abbey' on their local PBS stations for what has become a post-holiday tradition."

Rebecca Eaton, the executive producer of "Masterpiece," added, "Julian Fellowes has written every word of all four seasons of 'Downton,' and I toss him a huge bouquet on behalf of his American fans."