Benchmarking Software Development Productivity
This interesting paper by Maxwell and Forselius (IEEE Software, Jan/Feb 2000) attempted to produce benchmarks on productivity taken from a sample of 26 companies in Finland.
Unfortunately there wasn’t really enough data for many of the benchmarks to convey much meaning (e.g. they discovered that programming language used wasn’t significant, but had to note with this that this result may have been due to the fact that COBOL was used in most of the language combinations that had enough observations to analyse).
One interesting result from it, though, was the Mean Productivity index (in Function Points per month), that they produced from various business sectors (which was the 2nd most significant contribution to productivity variance, after the company itself):