Is 0.5% CTR minimum per keyword?

...or per ad group, etc

[limitup]

Does Google's 0.5% CTR minimum apply to each and every individual keyword? I always thought it applied to an entire ad group, but I was recently testing something that didn't work out too well and had a horrible CTR of about 0.2%. Now my ad isn't showing for that 1 particular keyword, so I am assuming it's because it has less than a 0.5% CTR after 1000 impressions (even though Google hasn't said anything about it yet). Is this why?

[Reflection]

Each kewyord has to maintain a CTR of atleast 0.5% for the last 1000 impressions or it will be disabled and later deleted. If this is the case the keyword will have a red * beside it.