Nickelodeon US is on track to record its best year ever, according to recent ratings from Nielsen, capping off 2008 as basic cable’s number-one rated network in total day, along with taking the top spot in all kids and tween demos.

Its popular pineapple-dwelling SpongeBob SquarePants will close the year as the top-rated series for kids two to 11, as he swims his way to his 10th anniversary in 2009, and iCarly is also topping the ranks as the number-one kids show on all of TV with kids six to 11.

The kidnet has been averaging a record 2.2. million viewers in total day this year, which is 42% ahead of the next closest-ranked network. It finishes with the top spot with K2-11 for the 14th consecutive year, earning a 3.5/1.2 million.

Noggin also posted its highest-rated and most-watched year with kids two to five and with total viewers, reporting double-digit increases from last year, prior to its split with The N. Delivery was up 39%. For its part The N, wasn’t too broken up about the split, also reporting its highest-rated year with its core teen demo (ages 12 to 17), up 25%, and Nicktoons Network also happy with its success in the six to 11 arena (up 33%) overall and 25% with boys six to 11.

The company’s digital sites also saw a healthy bump this year, with a monthly average of 131 million visits and 2.4 billion minutes spent by users across the sites. Its gaming sites saw 22 million unique players, bringing the year’s total game plays to 20 billion.