More than 86% of fatal dog attacks are done by this kind of dog:

[ozone_man]

79. Is Wikipedia ok?

It appears that pit bulls are consistently the number one breed responsible for deaths due to dog bites. They seem to be in the 40-50% range, while Rottweilers are in the 10-15% range. This is somewhat lower than the previous link, but it is the same two breeds that dominate. Face it Pit bulls are called that for a reason. They were were bred to be fighters, and killers, however sweet some may be.

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http://en.wikipedia.org/wiki/Fatal_dog_attacks_in_the_United_States

2006 30 Pit bull (14) (47%) Rottweiler (9) (30%) Mixed breed dog (4) (13%)
2007 34 Pit bull (14) (41%) Mixed breed dog (7) (21%) Rottweiler (4) (12%)
2008 23 Pit bull (12) (52%) Mixed breed dog (7) (30%) Husky (2) (9%)
2009 31 Pit bull (11) (35%) Rottweiler (2) (6%) Mastiff (1) (3%)

Mixed breed dog (11) (35%) Husky (2) (6%) Boxer (1) (3%)
Alaskan Malamute (1) (3%)
Weimaraner (1) (3%)

2010 36 Pit bull (15) (42%) Mixed breed dog (9) (25%) Rottweiler (4) (11%)
2011 31 Pit bull (14) (45%) Mixed breed dog (5) (16%) Rottweiler (4) (13%)
2012 34 Pit bull (13) (38%) Mixed breed dog (9) (26%) Rottweiler (3) (9%)