can't you just send integer data from server instead of strings? ie., do type conversion at server side.
by the way, parseInt(''1979') will return 1979 in Javascript.
So you may like to write a custom function to do the conversion at client
side and call it after line1={{=data}}.
Also, before trying these consider changing line={{=data}} to
line={{=XML(data)}} and see if that's working.
