Personalized date ring

M M.5 N N.5 O O.5 P P.5 Q Q.5 R R.5 S S.5 T T.5 U U.5 V V.5 W W.5 X X.5 Y Y.5 Z Z.5 Z+1 Z+1.5 Z+2 Z+2.5 Z+3 Z+3.5 Z+4 J J.5 K K.5 L L.5