This is a classic song, one of the first i learnt. I'm pretty sure this is a 100% but the rythm is your own style
I've tabbed it the way i play it. Enjoy, DUNNY!!!
^ - Upstroke
d - Downstroke
* - Skip stroke
Intro

e :---3---5---2---3---0---0---0---0--------------------------
B :-3---3---3---3---3---3---3---3---3------------------------
G :-----------------------------------0----------------------
D :----------------------------------------------------------
A :----------------------------------------------------------
E :----------------------------------------------------------


Main riff
    G       D      Cadd9
e :-3-------2-------0-
B :-3-------3-------3-
G :-0-------2-------0-    X 3 
D :-0-------0-------2-
A :-2-------x-------3-
E :-3-------x-------x-
   dd^     dd^   d^d^d^d^

    Am      G       C
e :-0-------3-------0-
B :-1-------3-------1-
G :-2-------0-------0-   X 2 (fist time round, only played once)
D :-2-------0-------2-
A :-0-------2-------3-
E :-x-------3-------x-
   dd^     dd^   d*d^*^d^

e :-2-2-2-2-2-2-2-2--
B :-3-3-3-3-3-3-3-3--
G :-2-2-2-2-2-2-2-2--      and repeat!
D :-0-0-0-0-0-0-0-0--
A :-x-x-x-x-x-x-x-x--
E :-x-x-x-x-x-x-x-x--
    d d d d d d d ^