CHICAGO TRIBUNE -- Feb 5 -- Fewer people are checking out online dating sites. According to Comscore, the number of visits in December dropped by 10% to 20.2 million Americans, compared with December 2006 figures. "There are fewer people, but they're more serious," says Mark Brooks, who provides marketing and other services for online dating sites. "The revenues continue to climb because the looky-loos have gone away; they can't get much service without paying a subscription to a Web dating service." "Paid online dating should grow from about $890 million in 2007 to an estimated $1.9 billion in 2012," says David Card, of Jupiter Research. The average monthly subscription is now $25 a month, up $20 a month from a few years ago, but more free sites might start popping up, thanks to the skyrocketing popularity of PlentyofFish. Plentyoffish.com is free and among the most visited Web sites -- not just dating sites -- in Canada and the U.S. Many so-called niche dating sites are growing, Farmersonly.com attracts those who like the agricultural way of life, while gk2gk.com appeals to self-described geeks. MyPartner.com welcomes gays and lesbians.