Despite high expectations, 1975 Houston Astros season was among the Astros worst in franchise history. Their record of 64–97 was far worse than even the expansion Colt .45s and would remain the worst record in franchise history until 2011 Houston Astros season. It was the worst record in baseball and manager Preston Gómez was fired late in the season and replaced by Bill Virdon. The Astros played .500 ball under Virdon in the last 34 games of the season. With Virdon as the manager the Astros improved greatly in 1976 finishing in third place with an 80–82 record. A healthy César Cedeño was a key reason for the Astros success in 1976. Bob Watson continued to show consistency and led the club with a .313 average and 102 RBI. José Cruz became Houstons everyday left fielder and hit .303 with 28 stolen bases. 1976 saw the end of Larry Dierkers playing career as an Astro, but before it was all over he would throw a no-hitter and win the 1,000th game in the Astrodome. The Astros finished in third place again in 1977 Houston Astros season with a record of 81–81.
Question: How many more games did the Houston Astros win in 1977 than in 1975?
Answer: 17