What's a steep climb to you?

So, I can handle 7-8% grade well enough, though I will be ready to croak if it's summer. I can do it though. This one road in my area though, it ranges between 11% and 20%. I pulled the elevation change over the run, splitting it into sections. And yeah, the steepest parts are 20%. I could not ride up it. There was absolutely no way, I walked my bike to the top. Is this a challenging grade for everyone, or can I get strong enough to do it?