Year identification

Stiebel Eltron is rather tricky.  The middle set of 2 digits is the date code. Add 25 to the 1st 2 digits to get the year and subtract 25 from the last 2 digits to get the week. Example: serial number of 031585-9426-001776 was manufactured in the 1st week of 2019. 94+25=119 26-25=1