What is the % of tax deduction on yearly earningsin CA USA?

It is not the same for every person, and it is not determined by percentage. There are different taxes, and medicare is the only one that is a fixed percentage for everyone. Each of the others is calculated using a non-linear formula. For example, social security is a certain percentage of earnings up to a certain amount, but nothing after that, while income tax is nothing up to a certain amount, then a low percentage up to another amount, and then a higher percentage after that.