This column was originally published on RealMoney on Oct. 18 at 12:46 p.m. EDT. It's being republished as a bonus for TheStreet.com readers.Looking at the highlights of the producer price index, or PPI, is like taking a time trip through key dates in U.S. history. Surging energy costs are the fuel for this trip, and they are also the source of a key debate facing both the Federal Reserve and investors, as the gain in overall inflation continues to be much larger than the gain in other prices. Whatever the case, the data will do little to ease concerns about inflation and will feed consumers' inflation expectations, which are already high. The producer price index rose 1.9% in September, which was seven-tenths of a percentage point more than expected and the largest monthly increase since 1990. It was also the second largest increase since November 1974. On a year-over-year basis, the PPI is now up 6.9%, the most since November 1990, when it was 7.0%. Excluding food and energy prices, the so-called core PPI rose 0.3%, one-tenth of a percentage point more than expected. The year-over-year gain in the "core" is now 2.6%, not far from the 14-year high of 2.8% seen in July.