My estimation based on the following Asian Development Bank paper available at:http://www.adb.org/Documents/Speeches/2004/ms2004017.asp
"Regarding the demand for gas, it is estimated that Pakistan's shortfall by 2010 will be 0.2 billion cubic feet per day (bcfd)., going up to 1.4 bcfd by 2015 and 2.7 bcfd by 2020."
These are last years estimates and probably at that time there was no Katrina or Rita, mean natural gas use would increase exponentially when there is rise in petrol prices. See rich people are also going for CNG, after this year's petrol prices increases. And also in Pakistan many new cities, towns and villages are going to be connected with natural gas network, so the depletion rate would be faster then esitmated.