If you go to the link toward the end of this sentence and enter "Upper South Carolina" as the name of the diocese and then go to "Church" (the third possible entry line) and enter "Trinity (Columbia, SC) " underneath the entry point (where you will see a list of parishes alphabetically in the diocese) then you can see in pictorial form some of the data from 2000-2010.
You may find the parish website there.
Alert blog readers may recall an earlier look at this parish on the blog in October 2010. A commenter on that thread captured the 1999-2009 data.
For the purposes of reference on the chart(s), the Episcopal Church Annual of 2007 (which is based on parochial reports of 2005) lists parish membership at 4000.