I took the figures from articles after a quick search, which I shouldn't have trusted that much, but here are primary sources from the Swiss statistical institute (in German):

• modal split time series (Excel) until 2008, in the total Swiss freight traffic (not just domestic).

• Transalpine traffic until 2008 (all crossings shown, not just Switzerland; "Schiene" = rail, "Strasse" = road; countries on the diagram below: France-Switzerland-Austria)
  

• Transalpine traffic in 2009 (pdf) in the preliminary release of the Swiss transport ministry in German; you'll find the 60.6% figure for rail in the before-last paragraph (or you can calculate it based on the second table on page 2, fields "Strasse CH" and "Schiene CH").

_{*Lunatic*, n.
One whose delusions are out of fashion.}