edited summary_statistics example
edited summary_statistics example

rdmenezes/thrust,google-code-export/thrust,UIKit0/thrust,malenie/thrust,allendaicool/thrust,lishi0927/thrust,hemmingway/thrust,lishi0927/thrust,Vishwa07/thrust,bfurtaw/thrust,malenie/thrust,levendlee/thrust,rdmenezes/thrust,h1arshad/thrust,julianromera/thrust,levendlee/thrust,allendaicool/thrust,bfurtaw/thrust,bfurtaw/thrust,google-code-export/thrust,Vishwa07/thrust,h1arshad/thrust,hemmingway/thrust,UIKit0/thrust,bfurtaw/thrust,julianromera/thrust,rdmenezes/thrust,julianromera/thrust,levendlee/thrust,Vishwa07/thrust,Vishwa07/thrust,levendlee/thrust,UIKit0/thrust,hemmingway/thrust,h1arshad/thrust,UIKit0/thrust,allendaicool/thrust,lishi0927/thrust,malenie/thrust,h1arshad/thrust,google-code-export/thrust,allendaicool/thrust,julianromera/thrust,hemmingway/thrust,malenie/thrust,lishi0927/thrust,rdmenezes/thrust,google-code-export/thrust