The answer is: It depends.
Surely having the PMP adds more value to you (you will be worth more in your eyes and the eyes of many companies out there), and the company should appreciate you more, but the percentage increase really depends on the company and, more importantly, your direct manager (who is usually the main person behind your raise).
Having said that, substantial salary increases when you gain any certification (not just the PMP) and you stay in the same company working under the same title are very rare. 30% increases are not impossible, but quite rare. Having no increase in your salary is common, and a small raise (3 to 5%) is mostly the norm if they want to increase your salary. If you have an excellent relation with your manager, you may get something up to 10%.
If you want to experience a jump in your salary because of your new certification, that you should start looking elsewhere. This is how you advance yourself. This is how you can get that 30% increase you want (or think you deserve).
Last advice on the subject, if you really love your company and your current job, ask for a raise, be specific about what you want. Ask for an increase you think they will give you (not something you think you deserve) and you know, they might just give it to you.