Passage: Written by Hiroya Oku, the manga chapters have been published in the Japanese magazine Weekly Young Jump since 2000 and is finished on June 20, 2013; the individual chapters of the series were being released approximately every fifteen days. Gantz is divided into three main story arcs referred to as "phases". After the completion of Phase 1, the author put the series on hiatus for a short time to work on Phase 2, which is also known as "Katastrophe". Phase 1 consists of the first 237 chapters. On November 22, 2006, the first chapter of Phase 2, chapter 238, was released. Phase 2 consists of chapters 238 through 303. The third and final phase began on October 1, 2009, after a brief hiatus. As of June 20, 2013, the main manga series is finished at 383 chapters long (not counting specials and spin-offs). The individual chapters are collected by Shueisha in tankōbon format; the first volume was released on December 11, 2000. Currently, 37 volumes have been released by Shueisha.

Question: When was publication of the manga chapters completed?
June 20, 2013