The year filter takes a range as its argument:
    year 2000
    year 2001 2005
It matches a game whose date field's year is within the year. It can be specified as a CQL parameter or in the body of the CQL file.

A year filter can be counted in which case it counts the year of the game, if that year lies within the range.

For example, to sort games by year, use:

     cql(input i.pgn)
      sort year 2000 2017
The year filter can also be specified on the command line using --year.