Simplify the following text for a Grade 8 native English-speaking person.
Original: That season , Boston won all but six games , finishing with a 38 â `` 5 â `` 1 record , which is the highest-ever winning percentage of any team in the NHL .
Simplified: Boston won all but six games , finishing with a 38 â `` 5 â `` 1 record , the best winning percentage for any team in a season .