Definitely list it. My D had 12 years of ice skating but never past immediate level due to both financial and time constrain but she still listed it in her activity list. So was her playing of music instruments, a decade of playing without any notable awards. Not every one is world beating musician or athlete, and for majority of the applicants, the activities are to show the admission officer that the applicants are consistent in pursuing their interest, rather than what have already been accomplished. D is enjoying her dream school now.