[EricH]

Depends what you're working on.

If you're dealing with motion, you'll be using it quite a bit (position-velocity-acceleration). MEs deal with motion a lot...

Controls and circuits use Differential Equations quite a bit; that's only learned after Calculus 2.

Statics and solid mechanics tend to use integrals and the like sparingly.

As far as proportion, it depends on what you're dealing with. You could probably get through 2 years in college without much calculus, but beyond that, expect about 25-30% of the work to involve calculus in some way, shape, or form; you might even be turning differential equations into algebraic equations.