Almost no one besides the publishers have numbers, but it is rare for more than 1 or 2 (probably sailor moon or fruits basket) shoujo books to be in the Amazon

Almost no one besides the publishers have numbers, but it is rare for more than 1 or 2 (probably sailor moon or fruits basket) shoujo books to be in the Amazon top 100 manga titles at a time. And that cool Josei title everyone is talking about was no where near that list. When the Manga boom was at it's height in the US (like 2005 or so) IIRC the consumers of Manga were something like almost 60% women or girls, and I doubt it has changed drastically. And while I remember Peach Girl and Nana and Hana Yori Dango (and the aforementioned fruits basket!) being popular at the time, I don't think they were 60% of the sales. And Shoujo is less successful in the US today than 15 years ago. (There are plenty of theories for why, elaborated elsewhere.)