almost all/the majority of U.S. economic activity

 

most /ˈmoʊst/ adjective

1 : almost all : the majority of — usually used before a plural noun ▪ Most people believe this. ▪ Most eligible voters went to the polls. ▪ I'm afraid of most dogs, but not this one. ▪ I like most foods. 2 : greatest in amount or degree
▪ Choosing a color took the most time. ▪ That family owned the most land. ▪ Unfortunately the negative aspects of our schools get the most attention.
for the most part
 
1 : almost all or almost completely
▪ Menu items are, for the most part, under $5. [=almost all the menu items cost less than $5] ▪ We wanted to keep it simple, and I think we were successful for the most part. 2 — used to describe a condition or situation that usually exists or is true ▪ Streets fill with people during the festival, but for the most part [=usually, most of the time] it's a quiet, sleepy town.