From XENON100 SD paper
https://arxiv.org/abs/1301.6620

Natural:

129 (spin 1/2): 0.264
131 (spin 3/2): 0.212

XENON100:

129 (spin 1/2): 0.262 (1% decrease)
131 (spin 3/2): 0.218 (2% increase)


 
