NEW YORK — The World Series television rating on Fox was up 17 percent over last year, but was the lowest for a matchup that went at least six games.

Boston’s 4-2 Series win over St. Louis averaged an 8.9 rating, 15 share and 14.9 million viewers, Nielsen Media Research said Thursday.

San Francisco’s four-game sweep of Detroit last year averaged a record-low 7.6/12 and was seen by 12.7 million viewers. That was among only three Series that had lower ratings than this year’s, joined by 8.4 ratings for Philadelphia’s five-game win in 2008 and San Francisco’s five-game victory in 2010.