That is good going. Considering that figure will also have included the time after they started to route people down to EDI, so the news that was taking place would have had a negative impact on numbers too, with many probably going to cheaper/more frequent EZY or KLM anyway.
I am not sure I buy the lack of cheap accommodation reason for people not showing up. Surely people wouldn't book flights without having at least searched for a hotel that meets their budget? I find Amsterdam a reasonable place to stay too, having spent many nights in the city om recent years.