As an expat and my parents living in India, I understand that it is my duty to support my parents. Even though my father is working and our family running without any deficit even without my contribution, I would like to chip in my part towards the income.

What percentage of salary according to Hindu philosophy should a son away from their parents should contribute to the Family income?

I am not married, if that is relevant. P.S I couldn't find an appropriate tag for this question, fell free to edit.