It used to be that for every 1 SteemPower earned, you also received 1 Tron.
From October 15th, the distribution changed to 1 SP: 0.5 Tron. See the following:
The change was supposed to come into effect yesterday (after Tron distribution was paused for three weeks while they finalised the coding changes).
Unfortunately the rollout didn't go so well, with many accounts not receiving their outstanding Tron. As usual there is no word from either steemitblog or steem witnesses as to when these issues will get fixed.
Anyway, the long and short of it is that with the Tron distribution halving, it's become less profitable to post on Steemit, especially as Steem Dollars are no longer being generated due to the Steem price being too low.