Here are the light novels sales rankings for the first half of the fiscal 2011.

Volume by volume (copies)
*1, 962,495 Moshidora
*2. 240,443 One Piece Strong Words vol.1
*3, 223,124 Baka to Test to Shoukanjuu vol.9
*4, 206,086 Toaru Majutsu no Index: New Testament vol.1
*5, 205,326 Kabukimonogatari
*6, 180,408 Ore no Imouto ga Konnani Kawaii Wake ga Nai vol.8
*7, 178,077 Hanamonogatari
*8, 171,476 IS: Infinite Stratos vol.6
*9, 168,478 Durarara!! vol.9
10, 162,836 IS: Infinite Stratos vol.7
11, 152,939 Boku wa Tomodachi ga Sukunai vol.5
12, 151,910 IS: Infinite Stratos vol.1
13, 145,523 IS: Infinite Stratos vol.2
14, 143,478 Gintama Kaettekita 3 nen Z gumi Ginpachi Sensei Returns
15, 140,817 IS: Infinite Stratos vol.3
16, 139,380 One Piece Strong Words vol.2

Author by author (copies)
*1, 1,123,683 Kamachi Kazuma
*2, 1,100,471 Arikawa Hiro
*3, 1,040,219 Yumizuru Izuru
*4, *,969,905 Iwasaki Natsumi ("Moshidora")
*5, *,695,053 Sakuraba Kazuki
*6, *,635,229 Nisio Isin
*7, *,624,064 Fushimi Tsukasa
**, *,472,409 Oda Eiichiro

Source: Oricon