The H.15 historical data is available through the Data Download Program at:
http://www.federalreserve.gov/datadownload/Build.aspx?rel=H15

This series, H15/H15/RIFLGFCM01_N.M, is available at:
http://www.federalreserve.gov/datadownload/Output.aspx?rel=H15&series=41e97c2acd1420d3a3ee55071da52e6a&lastObs=&from=&to=&filetype=csv&label=include&layout=seriescolumn