by Joy Victory, PayScale.com., 10/13/08 6:55 PM It's normal to wonder how and why you get paid the salary you do. After all, it's not a decision process most employers are willing to disclose, at least not without a little prodding. So what are the best-kept secrets when it comes to salary decisions at most companies? And how can you use them to your advantage? Let's take a look. 1. For most companies, 3.9% is the average budget increase for salaries. Yes, sad but true. According to the 35th annual WorldatWork Salary Budget Survey, the "actual increase in salary budgets was 3.9% in 2008." The number is expected to stay the same in 2009. This means, that for most U.S. workers, the average raise will be about the same, with "high performers" receiving about a 5% raise, and "low performers" receiving 2% or less, the survey authors note. "When people are looking for 6-8%, well, very few people are getting it," says Rebecca Mazin, co-found...