To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
Basically the pump gets less effective the more you use it. It gets to the point where you have to manually pull it up to be able to pump it. I even called Amazon customer service and had them send me a new one. The same problem developed over about the same amount of time. DO NOT BUY mDesign products.