I've seen it quoted in a bunch of places.90% in Germany! Wow! Hadn’t seen that number, where did you get it from? Somewhere in the forum here was an old discussion about comments by a German doc. His point was the diet and exercise (walking) routines of pipe smokers in Germany was such that many lived into their 80s and their deaths were old age and not cancer related. Good advice. Keep moving, and enjoy your life.
Filters aren’t about safety for me, it’s about keeping tar off my teeth and mouth and drying smoke.
Vauen's site says 95%, Interesting facts - https://www.vauen.com/filters/interesting-facts.html
I follow Bremanpipesmoker on YT and he's located there, he's mentioned many times that almost all pipe smokers in Germany use them.
I totally agree with you about exercise and walking. A famous pipe maker near me, Julius Vesz, is 90+ years old and recently retired. He would walk 4-5km a day to and from his workshop in the Royal York hotel (apparently).
I use 9mm filters because the smoke tastes better but I also like the fact I'm getting less tar in my mouth, double bonus. It's definitely a much drier smoke too.
Mediterranean diet, daily exercise, socialization/keeping busy, and moderate pipe smoking for relaxation are great recipes for longevity and a happy life.