experience

Use have, not make, in conjunction with experience, e.g.:

*I have often made that experience.

I have often had that experience.

As a verb, experience is not followed by a that-clause:

*I experienced that many foreigners do not know much about Germany.

In my experience, many foreigners do not know much about Germany.

It was my experience that many foreigners do not know much about Germany.

I found that many foreigners do not know much about Germany.