It depends on which timeframe you're talking about. I suppose if you take a snapshot at any given time, the concerns change. When there are concerns and we think we have the data that allows us to show that there is a problem or a safety deficiency demonstrated by more than one accident, we can conduct what's called a safety issues investigation. We're doing one right now in the air mode on post-impact fires in small aircraft. That's an example of how, rather than investigating here and here and here, we would pull together all of the data that is available on accidents within that category and do a complete analysis. Post-impact fires is an example of that.
On June 13th, 2006. See this statement in context.