On my sectional the variation is 9 degrees east. When I look at the AFD info an airport on my sectional the variation says "Magnetic Variation from 1980 is 12° East." Why would an FAA up-to-date sectional variation be different than an up-to-date AFD? And when I get a nav log done by the aopa the variation varies...it's not just 9 or 10, it's 12 sometimes. And my flight is all within 75nm.