- Aragorn
- [... 15 previous Chieftains of the Dúnedain ...]
- Arvedui, last King of Arthedain
- [... 14 previous Kings of Arthedain ...]
- Eärendur, last King of Arnor
- [... 7 previous Kings of Arnor ...]
- Isildur, King of Arnor
- Elendil, King of Arnor and last Lord of Andúnië
- Amandil
- [... 16 previous Lords of Andúnië ...]
- Valandil (First Lord of Andúnië)
- Silmariën (sister of Tar-Meneldur of Numenor)
- Tar-Amandil, King of Númenor
- Vardamir Nólimon, King of Númenor
- Tar-Elendil, King of Númenor
- Elros Tar-Minyatur, first King of Númenor
Total: 62 generations from Elros to Aragorn. If we assume all of his other ancestors were fully Man (probably not, as there was likely some inbreeding within royal families, but we have no evidence either way), he was (5/8)/2^62 = ~0.00000000000000001355% elven
All information for this ancestry came from http://lotr.wikia.com, I can't vouch for its accuracy or canonicity.