<prompt> Translate the following text to EnglishTangu mwaka 1991 BEA imekuwa ikitumia Pato la Taifa kama kipimo kikuu cha shughuli za kiuchumi kwa sababu Pato la Taifa ni sawa na viashiria kama vile uwekezaji wa ndani na uzalishaji.  <response>: However, since 1991, BEA has featured GDP as the primary measure of economic activity because GDP is consistent in coverage with indicators such as domestic investment and productivity. 