A fair number of 2015 convention attendance and baptism were tracked here:
https://www.reddit.com/r/exjw/comments/392far/2015_convention_locationdatesattendancebaptized/
Ballpark was about 0.5% of attendees were baptized.
2016 numbers appeared to be about 0.4%
So far, in 2017, there appears to be slightly less than 0.4% (but not by much).
The 2018 Yearbook numbers for the west should likely show slight overall declines in average publishers.
https://docs.zoho.com/sheet/published.do?rid=120417d3885200081425bb76fa549c306e1e6&mode=embed