It means that every full year of the patent from the date of application is a patent year. For example, if the filing date of a patent application is June 1, 1998, the period from that date to June 1, 1999 is the first year of the case, and from June 2, 1999 to June 1, 2000 The date is the second year of the case...the Nth year. The patent year is different from the calendar year.