The percent change defined as $100 \times \dfrac{\text{Total Number of Infected on day D} - \text{Total Number of Infected on day D-1}}{\text{Total Number of Infected on day D-1}}$ is also graphed below (scroll down). The rate of change gives the number of new infected as a percentage of the total number of the infected the previous day and is a good indicator that shows at what rate those already infected are infecting the others.