For anyone interested in kicking stats I found the excellent http://www.goalkickers.co.za which I think dantsw13 was referring to.
It goes back to 2012 and analyses the difficulty of kicks using:
• distance of the kick
• angle of the kick
• altitude
• side of field and foot used
• score difference (to indicate pressure)
• home/away
• 1st half/2nd half
I think the bloke is an actuary (plus a rugby nut). He uses the stats to produce rankings based on whether the outcome is better/worse the success probablity.
THe top 6 international kickers since 2012, in order, have been:
Leigh Halfpenny
Owen Farrell
Dan Carter
Greig Laidlaw
Nicolas Sanchez
Dan Biggar
Halfpenny is also the top rated kicker across all competitions.