XML to CSV

[search4u2003]

I'm trying to read Bandwidth utilization port wise, for which we are extracting the rrd data to xml and the to csv.
I need to know which value has to be calculated to get the exact data to tally it with my graphical interface.
Below is the example for it

Graphical value

Attached file

Csv Value
date val1 val2
6/21/2014 10500 27000
6/21/2014 10100 28300
6/21/2014 9050 23600