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Perhaps you've resolved to make 2015 the year that you finally get a big bump up in pay.

If so, you'll first have to clear the biggest hurdle standing in your way: You.

Less than half of working Americans ever even ask for a raise and close to 30% are uncomfortable negotiating salary, according to a new study by Payscale.

It may help you feel more confident to go after what you want if you know the odds are generally in your favor. Of people who have put themselves out there to request better compensation, three quarters saw their paychecks go up: 44% received the amount they asked for and 31% got an amount that was less than they asked for. (Hey, that's still something!)

That Payscale study also broke down the likelihood that those who ask shall receive based on annual salary, job, degree level, college major and state of residency.

You'll have the best shot if you...