ptr120: many of you cite the relocation of the German government to Berlin. Do any of you know how many years ago that actually happened!
Although I haven't been specifically watching the details, I expect that TXL frequencies got ramped up at the time to serve the new traffic. And that CGN has subsequently gone the common way of under-performing routes: Don't kill it straight away; let's see what we can do with (perhaps) smaller aircraft, (perhaps) fewer frequencies, (perhaps) more marketing effort; let's see if yields stabilise somewhere that we can keep running it at a decent profit. And that over time, the answer has proved to be no, and no in comparison with the better money to be made by redeploying the tangible and intangible assets elsewhere.