Data on historical interest rates in Germany

Anybody know of a website which gives a nice graph of interest rates over the last 30 years or so.

I'm calculating a mortgage with a fixed interest term of 15 years, and am assuming interest will rise from the current 5.5% to 10% at the end of this term. I'd like to know if 10% is pessimistic or optimistic.

Entwicklung der deutschen Hypothekenzinsen

Thanks Miwild, that shows it has not been over 10% for 26 years.

Doing a calculation for a Euro 60k loan at 5.54% simple interest fixed for 15 years.

With 1% Tilgung the monthly payments are 327, After 15 years 46015 principal would be left. If the interest rates went up to 10% that would case an increase in monthly payments of Euro 171. The term of the mortgage is 35 years

With 3% Tilgung the monthly payments are 427, After 15 years 18046 principal would be left. If the interest rates went up to 10% that would case an increase in monthly payments of Euro 67. So one is paying an extra Euro 100 per month now to save Euro 104 per month in 15 years time, and to reduce the term from 35 years to 19.