Anime portal site Anime-One held a 2011 summer female seiyuu election.
 The top 50 results :

Total vote = 51190
#01 Hanazawa Kana - 3736
#02 Tamura Yukari - 3710
#03 Mizuki Nana - 3524
#04 Asumi Kana - 2437
#05 Toyosaki Aki - 2386
#06 Taketatsu Ayana - 1950
#07 Chihara Minori - 1946
#08 Iguchi Yuka - 1680
#09 Tomatsu Haruka - 1617
#10 Itou Kanae - 1596
#11 Horie Yui - 1454
#12 Kugimiya Rie - 1409
#13 Yuuki Aoi - 1262
#14 Kitamura Eri - 1140
#15 Sawashiro Miyuki - 1114
#16 Hikasa Youko - 1095
#17 Shintani Ryouko - 1088
#18 Saitou Chiwa - 1021
#19 Noto Mamiko - 1004
#20 Kotobuki Minako - 967
#21 Koshimizu Ami - 940
#22 Inoue Marina - 931
#23 Hayami Saori - 901
#24 Takagaki Ayahi - 806
#25 Itou Shizuka - 761
#26 Sakamoto Maaya - 713
#27 Satou Rina - 706
#28 Yukana - 671
#29 Hirano Aya - 606
#30 Satou Satomi - 572
#31 Katou Emiri - 540
#32 Shimoda Asami - 528
#33 Kobayashi Yuu - 521
#34 Tanaka Rie - 476
#35 Kayano Ai - 473
#36 Nakahara Mai - 435
#37 Imai Asami - 396
#38 Hayashibara Megumi - 391
#39 Endou Aya - 376
#40 Makino Yui - 362
#41 Shiraishi Ryouko - 359
#42 Inoue Kikuko - 337
#43 Gotou Yuuko - 327
#44 Kanemoto Hisako - 324
#45 Oogame Asuka - 301
#46 Akesaka Satomi - 299
#47 Nanjou Yoshino - 255
#48 Sanada Asami - 253
#49 Shimizu Ai - 247
#49 Oohara Sayaka - 247

Ref :
http://anime.biglobe.ne.jp/userranking/cast/10044/

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'CuSO4' Yung