@Markus W
The taxable part is the amount that is more than what you invested, which sounds like $9000. If audited, the IRS is going to want to see reasonable, reliable proof of what you invested. That doesn't necessarily mean you need 20 years worth of canceled checks. If you have a table of your premiums, that's probably good enough, although you will have to convert the premiums from DM or Euros into dollars using the average conversion rate for each year, then add up the total in USD.
You won't get a 1099-R, so when you tell Turbotax you have retirement income "not reported on a 1099-R", the program will guide you to prepare a substitute 1099-R. The program may ask you for the tax ID number of the payer, which you also won't have since they are a foreign payer. I don't know the workaround for that, but @dmertz may know.
