Submitted 3 times in the last fortnight, popular in:

2017 (132 points, 10 comments) https://news.ycombinator.com/item?id=14536158

2013 (160 points, 59 comments) https://news.ycombinator.com/item?id=6232248

2011 (198 points, 53 comments) https://news.ycombinator.com/item?id=3410744

2011 (157 points, 26 comments) https://news.ycombinator.com/item?id=3400449