An annual bonus of 5-10% of your yearly salary is standard in a lot of industries, just as a 5-10% annual raise is considered standard. However, if you work on commission, you may see a significantly higher percentage. Your industry, company revenue, location, and level also heavily inform what's expected.
The bonus is typically calculated based on the number of months the employee has worked in the calendar year. Employees who have worked for the entire year usually receive a full bonus, while those who joined or left during the year receive a pro-rated amount.