Some stats from these great lists by CS:
I took the the first list from 04.2013, one from 03.2014 and the last one, 02.2015, equidistant and 11 months apart.
As a foreword, I've done this to cure my own curiosity. I'm not going to publish any names or look up any personal data on request. If some other general details might become interesting, perhaps I'm gonna elaborate them - I promise nothing!
The number of TLs rose from 443 / 924 / 1518, a steady progressive growth as it seems.
Level variations were 90/120, 89/127, 84/133, opening up.
The extremes in performance were:
+13 levels in 1 y, +25 levels in 2 y,
avg -14.52 in 1 y, -8.02 in 2 y (yes that's correct!)
The activities, visible in level-ups, are in two years:
about 200x 0 to 3 levels,
about 180x 4 to 8 levels,
with quite an even spread between 1 and 4 levels,
about 20x 9 to 25 levels.
Activities in one year, 2014 to 2015:
390x 0 to +1 level rise,
380x +2 to +3 levels,
maximum at 1-2 levels
85x +4 to +13 levels.
Of the 1518 names in the last list, 53 haven't changed their level nor their average number last year or even longer.
From the 2013 list, 6 have stopped in 2014 and 30 in 2015. From the 2014 list, 17 have stopped until now. I deem them as inactive or very low in activity.
Two players are visible in the latter category, constant level+average in 14, but a move in 2015 - they ARE active apparently.
Remember, no names!