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/RIFSGFSY01_N.WF, is available at:
http://www.federalreserve.gov/datadownload/Output.aspx?rel=H15&series=661f5cb2eb3542735b0d113a71a9a219&lastObs=&from=&to=&filetype=csv&label=include&layout=seriescolumn