Swagger, what day did you get 100% for Events? I'll just use the date of your post for now. In response to your question, for any new achievements, I'll probably just convert the percentages based on the new points. For previous 100% completions, I might leave a line somewhere indicating who got 100% before more achievements were added.
100% for Events and 16835
for me. Quick, but not as quick as Swagger.