Sources for macro economic forecast data I need data for these long run(atleast 10year forward) macroeconomic parameters from 2000, meaning I need forecasted data as in 2000 for 2010 so I can backtest my model with actual realised data: 

Long run aggregate gdp growth

Long run population forecast by age groups

Long run inflation forecast

Current account deficit forecasts

Kindly provide me all available sources to such data.
GDP: If I remember correctly, Congressional budget office offers 10-12 yr forward potential gdp every quarter, from which you can derive predicted potential growth. 

PopGrowth: U.S. Census has this data

Inflation: Fed Res/Philidelphia provides inflation forecast

Account deficit: All the sources for 5 or more years forecast in int. trade are either proprietary or highly unreliable. Best of luck in your search.