By Wojciech Kosc in Warsaw Poland’s industrial production declined 1.7% year on year at constant prices in May (chart), after a revised growth of 7.8% y/y the preceding month, unadjusted data from the statistical office GUS showed on June 20. The reading missed the consensus, which expected a gain of 1% y/y in the fifth month, even taking account of fewer working days. The calendar effect was the main driver of the May fall, analysts say. ‘Industrial production continued a period of heightened volatility due to calendar effects,” PKO BP said. That said, the calendar effect alone cannot explain…