don't store reference set if N<10
don't store reference set if N<10

Impactstory/total-impact-webapp,total-impact/total-impact-webapp,total-impact/total-impact-webapp,Impactstory/total-impact-webapp,total-impact/total-impact-webapp,Impactstory/total-impact-webapp,total-impact/total-impact-webapp,Impactstory/total-impact-webapp