Does anyone know the actual % effectiveness of masks (preferably including fabrics used in home-made masks)? It would be an easier sell to people if I could ju

Does anyone know the actual % effectiveness of masks (preferably including fabrics used in home-made masks)? It would be an easier sell to people if I could just say ,"it's not 100% effective but estimates by studies show it to be about 20% effective" I'm all for this. Can't hurt and might help.