From Wiki:
en.wikipedia.org
"Between the 1630s and the
American Revolution, one-half to two-thirds of
white immigrants to the Thirteen Colonies arrived under indentures.
[5] "
"Between one-half and two-thirds of European immigrants to the
Thirteen Colonies between the 1630s and the
American Revolution came under indentures.
[5] The practice was sufficiently common that the
Habeas Corpus Act 1679, in part, prevented imprisonments overseas; it also made provisions for those with existing transportation contracts and those "praying to be transported" in lieu of remaining in prison upon conviction.
[12] In any case, while half the European immigrants to the
Thirteen Colonies had been indentured servants at some time, actively indentured servants were outnumbered by non-indentured workers, or by those whose indenture had expired. Thus free wage labour was more common for Europeans in the colonies.
[13] Indentured persons were numerically important mostly in the region from
Virginia north to
New Jersey. Other colonies saw far fewer of them. The total number of European immigrants to all 13 colonies before 1775 was 500,000–550,000; of these, 55,000 were
involuntary prisoners. Of the 450,000 or so European arrivals who came voluntarily, Tomlins estimates that 48% were indentured.
[14] About 75% were under the age of 25. The age of legal adulthood for men was 24 years; those over 24 generally came on contracts lasting about 3 years.
[1] Regarding the children who came, Gary Nash reports that, "many of the servants were actually nephews, nieces, cousins and children of friends of emigrating Englishmen, who paid their passage in return for their labour once in America."
[15] "
I don't think the majority of the population were indentured, but a very significant percentage of the immigrants came over that way.