One guess and it begins with H according to the following piece from Zero Hedge :

Ignore for a second the sheer lunacy of anyone who thinks that the Greek government can grow GDP and decline the budget deficit in a straight line now that the country will see crippling strikes and rolling riots (not to mention blackouts) on a daily basis. But do note the black line, which shows the projected Debt/GDP ratio for the country as part of the bailout package. In essence Greece will go from having “only” a 133% Debt/GDP ratio to an insane 149% in 2013 before presumably dropping to 144% lower in 2014, still a good 11% higher than currently. Greece just got bailed out so it can get into even more debt! What psychopath of the Keynesian school thinks that this unbelievable trajectory is anything but a complete and utter waste of money? German, and US taxpayers, are merely giving Greece money so it can increase it debtor status with French and a few other European banks. To say that this is a viable solution is something that only those who bow at the altar of Alan Greenspan can do.

Taking the first point from the article on GDP growth in the face of strikes and fiscal armageddon, it appears, looking at the chart, that Greece has employed the UK treasury to produce the growth forecast as it looks just as improbable as the ones we got in the last budget.