thoughts.lua

local events_by_type={}
local event_types={}

for k,v in pairs(df.global.world.units.active) do
  if dfhack.units.isCitizen(v) then
    local mytypes={}
    for idx,event in pairs(v.status.recent_events) do
      local t=event.type
      if mytypes[t]==nil then
        if events_by_type[t] then
          events_by_type[t]=events_by_type[t]+1
        else
          events_by_type[t]=1
          table.insert(event_types,t)
        end
        mytypes[t]=true
      end
    end
  end
end

local function thought_cmp(a, b)
    return events_by_type[a] < events_by_type[b]
end

table.sort(event_types,thought_cmp)
for k,v in ipairs(event_types) do
  print(events_by_type[v],df.unit_thought_type.attrs[v].caption)
end

Prints good and bad thoughts experienced by your dwarves, in ascending order by number of occurrences.

(Perhaps age and severity should be taken into account, but that's trickier.)