Clinical studies often use Kaplan-Meier (aka survival) curves to show the proportion of patients that have survived after a certain period of time. There are a several articles that show you how to do the math:
Unfortunately, Excel does not include a function to graph Kaplan-Meier curves. You have to reformat the data to be able to create survival curves in Excel. Check out SCEW, an Excel add-in that allows you to create Kaplan-Meier curves. You do not have to download the add-in if you’re willing to manually type in the spreadsheet formulas that reformats the data (see Appendix A). Once you have reformatted the data, you can use the scatter graph function to create the Kaplan-Meier curve. For your convenience, I have created an Excel spreadsheet on Scribd that you can use.