Are no orphaned blocks mined in the Bitcoin network? I can't find orphaned blocks in the Bitcoin network from July with references to blockchain.info. 
Does this mean the bitcoin network centralization? 
I like C. Decker's paper "Information Propagation in the Bitcion Network." 
But if the stale rate is 0, this paper's equation can't apply to the Bitcoin.
probably the chart at https://blockchain.info/ja/charts/n-orphaned-blocks is broken. here you can see some new orphans blocks: https://blockchain.info/en/orphaned-blocks