cassanda cluster on AWS showing a total Owns > 100% in nodetool

I setup a 3 node cassandra cluster on ec2 and noticed somethign weird when I do a ./nodetool status. The Owns (effective) is > 100% in totoal.

[root@ip-10-205-116-141 bin]# ./nodetool status
Datacenter: us-east
===================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address         Load       Tokens  Owns (effective)  Host ID                               Rack
UN  10.205.117.246  85.73 KB   1       25.0%             72e2394c-bd17-4fe5-aee5-bf4cf8486153  1c
UN  10.205.119.47   89.91 KB   1       75.0%             7f39be54-5d74-433c-98e1-8aeff64ff795  1c
UN  10.205.116.141  171.17 KB  256     100.0%            ce5eb89b-d806-4d70-ab14-99df3bdee7c8  1c

shouldn't it be 33% each?