Bronze is pretty much the most durable metal you can get. Even better than SS. The only "problem" is that it turns green (verdigris) with age because of the copper in it -- think: Statue of Liberty. However, it's not really a problem functionally as this is it's natural way of protecting itself. The coloring is just aesthetic. The fancy chrome coating is the delicate part. So... 16 years old? They're still just a infant.
You can clean them up if you want and maybe put a protective clear coat on there - but you'll need to re-do that every so often.