You first need to know which species are endemic. Then you simply calculate their overall ratio across all species, the sum of exotic, native and endemic :)
Abbas Naqibzadeh Sean Patrick Flynn thank you so much. Andrew Paul McKenzie Pegman so the ratio would be in decimals and can be used for equations right?
By using diversity indices, you can have an idea about species richness, evenness, proportional abundance or dominance. But not specifically say about endemic richness. I suggest you to use ratio suggested by Taniya Talwar
Jefferson Himson , R M C S Ratnayake thank you so much. I did follow the ratio method explained Andrew Paul McKenzie Pegman . It is easier to follow once you have all the total species list in hand.