there are a few here but they are not very accurate.
chipped in and out alot so I know approx if it will help?
From 1-3000 skills: 3 ESI
From 1-4000 skills: 6 ESI
From 1-5000 skills: 11 ESI
From 1-6000 skills: 19 ESI
From 1-7000 skills: 27 ESI
From 1-8000 skills: 37 ESI
From 1-9000 skills: 47 ESI
so if you have 3100 skills you will be able to fill 3 ESI ect