they dont, the hash rates listed are not accurate at all. this has been confirmed by the pool operators too, look a few pages back or so because of the new algorithm.
XeBdxWotzpPAjP1AUA3djCFnzd747h9Diq 160,301 99.409% 572.6623 Mh/s 2014-07-12 08:37:35
XdSBqrgoftK6u1JbzM8i3ExdT4oKqE9z2t 492 0.305% 4.4739 Mh/s 2014-07-12 08:37:39
Xgkgpv5wAWkhkXxGEtvK9n3JxKeM64RJR9 184 0.114% 916.2597 Kh/s 2014-07-12 08:37:26
XkXpfcrqsNRhp6XWKFsZWsmhENh5KHMMcg 88 0.055% 610.8398 Kh/s 2014-07-12 08:36:56
Xuma6UW6BB3nhJUZfA8YYU8Q7mXi4vhL9E 69 0.043% 305.4199 Kh/s 2014-07-12 08:36:45
XtHxmu97GrYnK59FCNnd7iDfwz2ubg2tRV 59 0.037% 305.4199 Kh/s 2014-07-12 08:35:50
XqQCX8DYJbJSpmYZMXwCfm2TPDNinh7Btd 26 0.016% 0 2014-07-12 08:23:47
XhVxSNkvRYPK6nUT9GcuEfxCQjX6wn3hKB 20 0.012% 0 2014-07-12 08:16:18
XiLEJNg8JATuacLhUFa7rRgtLPer56EbKF 16 0.01% 0 2014-07-12 08:28:29
you are telling me hash is not accurate but the top person gets 99% anyway?