The top manga properties in North America for 2012, compiled by ICv2 based on sales through all channels, show long-term power brands at the top of all charts.  Viz's Naruto, the #1 shonen property as well as the #1 property over-all, has been released for nearly 10 years in the U.S.  Sailor Moon, the top shojo property and the #2 property over-all, is even older.

Of the top ten manga properties in 2012, only one, Blue Exorcist, launched here less than three years ago.  Over half are five years or older in North America.

This phenomenon is in part the cumulative effect of manga volumes:  the more volumes, the more sales, and the longer something has been coming out, the more volumes (usually).

Sailor Moon is something of an exception.  It launched over a decade ago, was a hit then, and went through a fallow period when it was out of print here.  Then it came back with a bang in new Kodansha editions, and is having a second life as the top shojo property despite having relatively few volumes available here.

For the Top 25 Manga Properties in 2012, click here.
For the Top 10 Shonen Manga Properties in 2012, click here.
For the Top 10 Shojo Manga Properties in 2012, click here.