What kind of projection are you doing? What sort of data are you working with? Excel has a number of functions for doing projections, but you have to have a mathematical model before you plug numbers into it. (Okay, you don't have to have a model, but I'm assuming you want a useful result. Otherwise you could just as easily make stuff up; the RAND() function is quite good at that.)
From the data I see, there's no discernible pattern to it. Cooper, for example, did 57 of something in 2006/07, 39 in 2007/08 and 6 in 08/09, so he should be doing negative something at the end of 08/09, but if he's selling things that's probably not possible. Other people are going up and down without any rhyme or reason. It doesn't help that I have no idea what these things you're totaling are.