I would say a laymen's view would be HK hotels at greater than 95% capacity. I would assume that the no. of rooms available is at maximum capacity (?) But that doesn't take into account the people streaming in from the border.
Edit: Just reading on the Govt website that hotel capacity is 87% so my theory is most likely wrong. Total of 64,000 hotel rooms available in HK, 42 million visitors with nearly 70% now coming from the mainland.
I would be interested to know how many are the suitcase carrying day trippers with their own 'import business'.