The following chart was inspired by a similar chart on the blog Experimental 3-6-1. It displays the ratio between the average number of shots a team needs to score a goal, versus the average number shots they face before they concede. Click the image to zoom in.
From the graph, we can surmise that Borussia Moenchengladbach has by far the sturdiest defence, while Freiburg offer about as much resistance as wet paper. The most inefficient teams in front of goal, however are Cesena and Kaiserslauten. It's probably no surprise that both are in severe danger of relegation.