How many more games did the Houston Astros win in 1977 than in 1975?
return Houston Astros ;return games that #1 win ;return #2 in  1977 ;return #2 in  1975 ;return number of  #3 ;return number of  #4 ;return difference of #5 and  #6
['select', 'project', 'filter', 'filter', 'aggregate', 'aggregate', 'arithmetic']