And how well is that doing, over the course of its entire existence?

As well as the Dvorak keyboard layout, I imagine

Dvorak is something anyone can use on their own any time. I imagine it is much more successful than Esperanto, because the only point of language is communication. It is the Facebook problem - you need a large network of participants to make a language work, or the language fails its purpose.

Also, Esperanto is ugly as fuck. It has I believe 4 accented letters, and I have no idea why anyone would think when divising a new language that accents or umlauts are good ideas (unless all the letters supported them and had consistent meaning). Otherwise, just use new characters.