1. A method for displaying a statistical chart, comprising: providing a processor that implements: determining whether a screen rotation event of switching from portrait-orientation display to landscape-orientation display is received, and obtaining additional to-be-shown data added during switch from a portrait-orientation-display drawing area to a landscape-orientation-display drawing area if yes, and drawing the landscape-orientation-display drawing area; and displaying a statistical chart in the drawn landscape-orientation-display drawing area, the additional to-be-shown data being shown in the statistical chart; wherein the displaying a statistical chart in the drawn landscape-orientation-display drawing area, the additional to-be-shown data being shown in the statistical chart comprises: determining a coordinate change relationship between a coordinate system of the portrait-orientation-display drawing area and a coordinate system of the landscape-orientation-display drawing area based on the determined portrait-orientation-display drawing area and landscape-orientation-display drawing area; extending, in the drawn landscape-orientation-display drawing area, a statistical chart in the portrait-orientation-display drawing area based on the coordinate change relationship between the coordinate system of the portrait-orientation-display drawing area and the coordinate system of the landscape-orientation-display drawing area; and showing the additional to-be-shown data in an extended display part of the statistical chart that is extended in the landscape-orientation-display drawing area.