OK, good to know. Without a decent history of training, setting a fairly arbitrary goal like w/kg can lead to issues when people miss it for a range of reasons. We are not all meant to get there, unfortunately. Adding in your current age is also very important. That Coggan chart is not necessarily aligned for those of us with 4 decades under our belts 
I don’t mean to dissuade you from that if it’s what you want, but it’s important to set goals that are achievable, while still being a reasonable challenge. For reference, this 4w/kg goal comes up a LOT, and you can see the related discussions, how people hit or missed it, and some other ideas for goals besides that one (which can be elusive).