I thought I’d reviewed a lot of books, but then I noticed Nenia Campbell. She’s currently ranked the No. 1 reviewer on Goodreads, the social book site with more than 25 million members.

So far this year, Campbell has reviewed 1,557 books. About 20 a day.

[CORRECTION 3/28: Suzanne Skyvara, a spokesperson for Goodreads, tells me that by “this year” the company means “in the last 12 months.” In that case, Campbell’s pace is a leisurely 30 reviews a week.]

The most recent Pew Research study indicates that the typical American reads five books a year. Campbell reviews that many before brunch. Not that she has time for brunch.

Campbell is an exceptional example of the revolution in user-reviews made possible by the Internet and encouraged by Amazon, which bought Goodreads last March. Not long ago, it would have been impossible to imagine so many people voluntarily contributing so much of their time to this endeavor. For social media sites, these fanatical users provide free content and increased screen time. For retailers, they offer free feedback to guide other consumers.

“In all honesty I treat my reviewing as a job,” Campbell says, “so I spend most of my time reading, reviewing, and writing books because I see this as my career.”

But what’s the payoff for this San Francisco-area writer? “I’ve always hoped my hard work on Goodreads and the books I publish will bring me to the attention of someone.”

Campbell describes herself as an omnivorous reader — “from Jane Austen, to 1970s bodice rippers, to contemporary books about the philosophy of physics.” Most recently, she panned a graphic novel called “Dreary & Naughty: Friday the 13th of February,”  by John LaFleur and Shawn Dubin: “The pictures are pretty good but I can’t, in honesty, give this book a high rating because the poetry — the poetry was awful.”

1 Star.

“A review is worthless unless you say what you really think,” Campbell tells me. “It has to come from the heart. In one of my philosophy classes we learned about something called ‘qualia,’ which is the word for the embodiment of subjective personal experience. I think the best reviews come close to capturing the qualia of reading a book, and portraying what it was really like for you to read that book.”

Campbell has captured a lot of qualia. And she’s not about to take a break. She lists 5,503 books on her “to read” shelf. “I’m a speed demon,” she says.

She’d better be. With 1,461 reviews for the last 12 months, No. 2 Goodreads reviewer Samantha of Cincinnati is gaining on her. “It’s lovely to see others who have the same passion for reading and reviewing that I do,” Campbell says, but “I’m not going to give up my place easily.”

Authors and publishers sometimes send her advance copies of upcoming books. “The UPS guy is on a first-name basis with my family and me,” she says.  “I read more e-books than I used to since I started receiving so many digital copies of books for review. I prefer the physical copies though. It’s nice to be able to feel the book in your hand. Also, you can throw a physical book around, or sit on it by accident, and not have it break or run out of battery power.”

When she’s not reviewing books on Goodreads, she’s writing them. “I’m currently in the process of finishing what will be my 12th published book,” she says. “I write dark romance and erotica, urban fantasy, and science-fiction, but one day, I’d like to try my hand at each of the main genres. My two most popular books are ‘Fearscape,’ about a girl who gets romantically entangled with a burgeoning serial killer, and ‘Cloak & Dagger,’ a romance between a contract killer and his hostage.”

She lists more than 23,000 books on her Goodreads shelves. “Only three words matter,” she tells me: “Need More Books.”

But as fast as Campbell has been reviewing, she barely makes the top 100 for Goodreads’ all-time most prolific reviewers. Top honors there go to Dolly Martino in Lorton, Va., who has posted a staggering 8,406 reviews.

In the time it’s taken me to write this blog post, I should have reviewed 16 books.

(Disclosure: Jeffrey P. Bezos, co-founder and chief executive of Amazon.com, owns The Washington Post.)