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/RIFSRP_F02_N.A, is available at:
http://www.federalreserve.gov/datadownload/Output.aspx?rel=H15&series=83473b9504f94930e287d23d2b9e1f64&lastObs=&from=&to=&filetype=csv&label=include&layout=seriescolumn