Not really about volume as much as the # amount of shares there are out there available to be. Here there are just 13k total.
It's like if you have a product to sell in your city or state. If there are 100,000 people that live in your area and you have 500,000 items of your product you can't really get a ton for the item as you have a ton of them in relation to the amount of buyers there would be. Now, if you only have 100 of your product and there are 100,000 potential customers..... now you can get more cuz there is more demand for the item than you have. It's all about supply and demand. Here the supply is only 13k of which 5-6k are already bought up by people like us here on the board.