Salary data is considered by many to be exclusionary. That means it will be used to eliminate you from consideration - unless you are underpaid and applying to a new employer who wants to underpay you. If you make too much, then he will think that you would be unhappy with his company. If you make too little he will undervalue your claimed experience and skills. If you used to make more than you do now, he will think you are a poor risk. If you are comfortable providing salary information then give it but if you are not, you are not alone. 

Remember, too, that your salary is confidential information. Many people may see that information prior to the hiring manager and you may never be called for an interview; yet, many people now know how much you are paid. 

Something like this works...Salary history is confidential information to be supplied in the interview - or - I have always been paid a salary commensurate to the job I have held. I assume you will do likewise. 

If you feel that you need to provide salary information this is how you figure it out. 

You have to add up your total compensation package of cash and extras. There is a difference between take home pay and a total compensation package.  

Take your base pay + estimated bonus + next raise (if soon) + the value of your extras (company auto plus mileage per year + matching contribution to company sponsored retirement plan + life and health insurance + any other company compensation or benefits) = Your Compensation Package. 

Give your salary history on a separate sheet of paper or in your cover letter, but never in the résumé. No matter what an employer asks for, you can always give him less. Some people give information only on their last job or the last ten years. Normally salary tables give each employer's name, followed by your title, dates of employment, and ending salary: 

XYZ Company, Denver, Colorado, 1990-1998 Store Manager Salary: $47,000 plus incentives and bonus 

Another way of handling it is to say something in your cover letter: 

Base salary was in the mid-40s, plus a good benefits package and bonus – amounting to considerably more.