I expect once a year..
I agree that this fixation on the Titanic seems a bit strange, as there have been worse sea disasters. i.e WWI/WWII
The Titanic sinking may appeal to those who have a dramatic nature. As unfortunate as the collision was, I think the pre-occupation with it is romantic dribble..
Perhaps this site is suitable for those interested..
http://www.titanic-voyage.com/overview/