Decimal Seperator in Highcharts / HTML5 and reports

Hello,

i think this is an easy one for the experts, however I am lost...:)

When logging in to Jasperserver I set the locale to DE_de and expect the decimal seperator to be "," and not ".".

However in all tables and charts I still have the english number format.
 

How can I change this, especially for HTML5 Charts.

Thanks for your help,

Philipp