display error message with google chart

Dears ,

i create google chart with dropdownlist  menu to select records from SQL DB and display to the chart depend on years , and its working fine no issue for that but when i am select year that dosnt have record it give me this error on chart 

'Data column(s) for axis #0 cannot be of type string×'

i need to display error message that (Unable to load chart as there is no record found for selected years ).

here is my code:-

C# code:

[WebMethod]
public static List