To further your point, let me mention this (I'm pretty sure this is accurate):
In less than a year (starting Nov. 2010), 16 girls have left the H!P Eggs. Two debuted as soloists (Kikkawa Yuu, Kitahara Sayaka), seven left to form K-pop dance group Up Up Girls (Sengoku Minami, Mori Saki, Furukawa Konatsu, Sekine Azusa, Arai Manami, Satou Ayano, Saho Akari), one was added to Morning Musume (Fukumura Mizuki)and six disappeared w/o any specific notice (Kizawa Runa, Tanaka Anri, Sainen Mia, Okai Asuna, and Hirano Tomomi, Maeda Irori).
In 2011 there have been 7 new Eggs added (Jan Dayeon, Yoshihashi Kurumi, Hamaura Ayumi, Taguchi Natsumi, Ootsuka Aina, Mogi Minami, Ogawa Rena). Added to the other remaining 8 continuing Eggs (Nagasawa Wakana, Takagi Sayuki, Kaneko Rie, Takeuchi Akari, Katsuta Rina, Miyamoto Karin, Kudou Haruka, Tanabe Nanami), there are 15 girls in total.
...this could change in a matter of hours.
