14 years
Certainly list all events in the city on your website, but I don't think further promotion is useful.
Let's think about this. If someone is planning a touring trip (say 28 days covering 6 countries) it's likely that they will have already decided on the dates for Berlin (+- 3 days) before they look at your hostel. Any events outside that period will be of no use to them. They just might change the dates to suit an event that you mention.
If someone is a big fan of, say, speedway racing, they will have looked for all such events in the country, or may even be planning their trip around such an event. So, for such a person, they will have decided they want to be in Berlin on specific dates before they start looking for where to stay. Your main job is therefore to attract them to your hostel RATHER THAN any others.
Log in to join discussion