Statistics Tab consists of three segments:
This diagram shows what portions of your measurements belong to which hypertension category.
Blood pressure graph represents propagation of your measurements across blood pressure categories. You can see how many measurements are classified as a hypotonia(under lines of heart icon) or measurements, which says that pharmacological treatment may be required (above pill icon).
With blood pressure factor you get overall perspective over your measurements regarding hypertension.
This graph simply shows how many measurements are classified to which category in a specific time.