<prompt> Translate the following text to EnglishMfumo wa FGD wa kitengo kimoja umefanywa katika miezi 20 hadi 21, na mifumo mingi ya FGD imewekwa ndani ya miezi 36.  <response>: Single-unit FGD installations have occurred in as little as 20-21 months9, and multiple FGD systems have been installed within 36 months. 