Yesterday the NPD Group issued a report on U.S. tablet sales in the U.S., from January through October of 2011. Worth noting up front is that the numbers in this report are about sales — actual tablets sold to actual customers — not “shipments” from the factory to stores and warehouses.Much-reported on is that second-place went to HP, after its fire sale on the discontinued TouchPad. What hasn’t gotten much commentary is the extraordinarily contorted way that NPD reported these numbers.The report begins (emphasis mine):U.S. tablet sales, exc...