question: How many fewer H-1B visas were issued in 2010 than in 2011?
#1 return H-1B visas 
#2 return #1 issued in  2010 
#3 return #1 issued in  2011 
#4 return number of  #2 
#5 return number of  #3 
#6 return difference of #5 and  #4