http://www.everyculture.com/multi/A-Br/Afghan-Americans... Large numbers of Afghan refugees began arriving in the United States in 1980 in the wake of the Soviet invasion. Some were officially designated as refugees, while others were granted political asylum. Others arrived through a family reunification program or by illegal entry. About 2,000 to 4,000 Afghans arrived every year until 1989, when the Soviet Union withdrew its troops. Estimates of the number of Afghan refugees in the United States ranged from 45,000 to 75,000. Read more: Afghan Americans - History, Modern era, The first afghans in america, Significant immigration waves, Settlement patterns
http://www.everyculture.com/multi/A-Br/Afghan-Americans... In addition to the refugees that were parolled into the US there were another 20,000 that were issued visas.
So following the Soviet invasion where the US had little contact or involvement roughly 100,000 Afghans were taken into the US over a 9 year period because the annual number allocate for Afghan refugees was very low creating a long waiting line of several years for some. In fact out of the world wide numbers allocated by the State Department Afghan refugees were given a very small allocation and in the screening process only about 1 out of 5 of those that applied were able to get a resettlement number.
Most refugees do not want to resettle to the US for ideological reasons and I have seen Viet Cong leaders beg to be allowed entry into the US. Their motives reflect the motives of most people who are parents, stability, electricity, schools, clean water and food. Everytime the US has initiated efforts to resettle refugees the system is swamped with people who want to be taken. many who have no ties to the US at all. When people have had an association with the US those numbers go up by a large factor.