If a 4.5% decline rate is used, then Sam's 2020 forecast would increase from about 58.5 mbd to just over 61 mbd, excluding yet to be sanctioned projects, shown below.

source: http://en.wikipedia.org/wiki/Oil_Megaprojects

As is explained in the story itself, the rational for utilizing 4.35% is detailed in the TOD article The 2008 IEA WEO - Production Decline Rates.

Eeery how the observed data is roughly tracking your forecasts. Great work as always, I'd wondered about that ca. 1 mb/d gap before, from simply eyeballing charts.

Minor editorial quibble: there's a big chunk of text in the story which is blocked out, I assume it's your own words though.