That year he also led the league in fielding (.994) and set a NL record with 159 double plays, breaking Frank McCormicks mark of 153 with the  Cincinnati Reds; he broke his own record in 1951 with 171, a record which stood until Donn Clendenon had 182 for the 1966 Pittsburgh Pirates. He finished 1950 third in the league in both homers (32) and RBI (113), and came in eighth in the MLB Most Valuable Player Award voting. In 1951 he became the first member of the Dodgers to ever hit 40 home runs, breaking Babe Hermans 1930 mark of 35; Campanella hit 41 in 1953, but Hodges recaptured the record with 42 in 1954 before Snider eclipsed him again with 43 in 1956. His last home run of 1951 came on October 2 against the New York Giants (NL), as the Dodgers tied the three-game NL playoff series at a game each with a 10-0 win; New York would take the pennant the next day on Bobby Thomsons "Shot Heard Round the World (baseball)". Hodges also led the NL with 126 assists in 1951, and was second in HRs, third in run (baseball) (118) and total bases (307), fifth in slugging average (.527), and sixth in RBI (103).
Question: How many years had the NL record for double plays stood when Donn Clendenon broke it?
Answer: 15