How to write Multi Parameters in MDX when using Dynamics OLAP

Hi,

Now I am making a report using Dynamics OLAP to display the sales data for all sales persons and be filtered by Year. but now, I just can enter one value at @Year parameter. How can I do if I want to enter multiple value? How to write it?

Followings are the current statement:

select NON EMPTY {[Measures].[Total line sales],[Measures].[Total line cost net WAR],[Measures].[Line margin]} ON COLUMNS,
NON EMPTY {[NM Commission sales group].[Group name].CHILDREN}
ON ROWS
FROM [NM Sales cube]
WHERE (STRTOMEMBER("[NM Date].[Year].&["+@YEAR+"-01-01T00:00:00]"))