Japan Mint had to stage a lottery after it was overwhelmed with demand for a proof coin set engraved with the final year of the current Heisei era, officials said Monday.Some 210,000 orders were placed for the set of six coins, featuring "Heisei 31", during last month's sales period. Japan Mint usually markets 30,000 sets for such annual releases.Following the deluge of orders this year, it will increase production to about 50,000 sets.Even so, it looks as though approximately 160,000 numismatists will be left empty-handed after the lottery, which took place Feb. 14. Some of the sets are al…READ FULL ARTICLE