Stipping more than one table in a page

Stipping more than one table in a page

Hello 

I am trying to strip my tables using jquery while selecting the even rows (tr:even) and giving it a class with a different background. The page has more than one table which should be stripped. The problem that all the tables are stripped but as if they are one table. I mean that the odd or even counting continues from the first table to the second one. 

Is it a usual behavior?! can anyone help me to make it deal with every table separately (start counting the odd or even for each table separately)?

Thanks