Data protection notice for the “Piwik” web analysis service:
Our website uses Piwik, which is a web analytics service. Piwik uses cookies, which are text files saved on your computer. These enable us to analyse how the website is used. For this purpose the usage information produced by the cookie (including your shortened IP address) is transferred to our server and saved for user analytics, which assist us with website optimisation. Your IP address is immediately made anonymous during this process, so that you remain anonymous to us as a user. The information produced by the cookie about your use of this website is not passed on to any third parties. You can prevent the use of cookies by the appropriate setting on your browser software; however, it may then be the case that you cannot fully use all the functions of this website.
If you do not agree to data from your visit being saved and analysed, you can subsequently indicate your disagreement to having your data saved and analysed by a click of the mouse at any time. In this case, an opt-out cookie is stored on your browser which results in Piwik collecting no session data whatsoever. Notice: deleting your cookies also has the effect of deleting the opt-out cookie. This must then be reactivated by you, if necessary.
You can decide here whether to allow a unique web analytics cookie to be stored on your browser, and which enables the owner of the website to record and analyse a variety of statistical data. 
If you would like to disagree with this, click on the following link to store the Piwik deactivation cookie on your browser.