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/RIFLDIY02_N.B, is available at:
http://www.federalreserve.gov/datadownload/Output.aspx?rel=H15&series=45a569f4726529f59e1f4b75462dc7f9&lastObs=&from=&to=&filetype=csv&label=include&layout=seriescolumn