It is possible to have zero statistical volumes when a tape is reused. For example, on Monday, data set A resides on Volume 1 and causes one mount. On Wednesday, data set B resides on Volume 1 and causes one mount. Thus, there are two mounts for one volume. Since Volume 1 is reused, data set A has zero statistical volumes and one statistical mount, while data set B, the current version, has one statistical volume and one statistical mount.