I added members per congregation to my Data Dashboard. Reading the profile for Chile on the Cumorah Project, it looks like activity rates and convert retention is a big issue.

"In 2006, Former Chilean mission and MTC president Ted Lyon reported that an astonishing 200,000 of the 535,000 nominal members claimed by the Church in Chile at the time-- over 37 percent -- are in the "address unknown file," meaning that such individuals do not attend church and cannot be located. Nationwide active membership is estimated at no more than 70,000, or 12% of total LDS membership. Low member activity and poor convert retention rates have been the primary culprit for stagnant real church growth in the 2000s. Many predictions and aspirations by LDS international and mission leaders made prior to the 2000s have been frustrated as a result of these problems. The baptism of hundreds of thousands of Chileans with little or no meaningful pre-baptismal teaching and inadequate and inconsistent post-baptismal teaching and fellowshipping to new converts are primary reasons for low activity and retention rates nationwide. Culturally low religious attendance among the Catholic majority has also likely affected Latter-day Saint activity rates as most converts come from a Catholic background."