Moving monthly Total Data / day

all values are listed as: GB

      time  |    total
------------+---------
2009-12-26  |  120.290
2009-12-27  |  121.340
2009-12-28  |  120.652
2009-12-29  |  113.473
2009-12-30  |  114.699
2009-12-31  |  112.610
2010-01-01  |  111.257
2010-01-02  |  104.443
2010-01-03  |   99.802
2010-01-04  |   97.847
2010-01-05  |   97.149
2010-01-06  |   95.834
2010-01-07  |   94.452
2010-01-08  |   94.406
2010-01-09  |   99.815
2010-01-10  |  107.795
2010-01-11  |  122.797
2010-01-12  |  121.252
2010-01-13  |  120.192
2010-01-14  |  118.812
2010-01-15  |  116.332
2010-01-16  |  115.652
2010-01-17  |  128.449
2010-01-18  |  131.453
2010-01-19  |  127.039
2010-01-20  |  120.814
2010-01-21  |  120.623
2010-01-22  |  120.771
2010-01-23  |  117.045
2010-01-24  |  116.941
2010-01-25  |  116.864
2010-01-26  |  114.470