<prompt> Translate the following text to EnglishKatika makadirio ya mapato ya baadaye na faida, wataalamu wa fedha katika Utawala wa Usalama wa Jamii na Utawala wa Fedha za Huduma za Afya hutumia dhana mbadala kuhusu mwenendo wa kiuchumi na idadi ya watu, ikiwa ni pamoja na mapato ya wastani, vifo, uzazi, na uhamiaji.  <response>: In projecting future revenues and benefits, actuaries at the Social Security Administration and Health Care Financing Administration use alternative assumptions about economic and demographic trends, including average earnings, mortality, fertility, and immigration. 