Let's start by looking at the size of the daily reward pool.
This excellent post by @penguinpablo from 8 months ago calculated that roughly 48'000 steem are added to the reward pool each day. Based on the last 3 months, I calculate that the figure is roughly 49'000 steem per day. - So we are roughly agreed on the number of steem available to be given away daily at 49'000 steem.
If we take the current price of steem (USD 2.50) this gives us around USD122'500 to be given away daily (the figure could be slightly different depending on the price of the SBD).
On a typical day, there are around 58'000 active users who post at least one blog or comment.
On an average day there are around 68'000 new blogs and around 152'000 new comments. This means that the average user is posting around 1.17 blogs and 2.62 comments on the days when he is active.
Breaking these numbers down tells us that an "average" user earns around USD 2.11 for each day he is active.
If we assume blogs earn ALL of the reward, and comments earn nothing, then each blog would earn $1.79 on average.
In practice comments do earn more than nothing. Many comments get rewarded. I don't know the exact ratio of rewards per comment compared to rewards per blog. If I assume that comments earn one-tenth of an average blog then the average reward split would be:
The average daily user
If you are an "average" user, you will be making around $2.11 per day when you are active. In some countries, that's a lot of money. In others it is well below the minimum hourly wage.
If your blogs are making more than the average of $1.64, per blog then you are already doing well on Steemit.
There's no such thing as an "average" user
Nobody writes exactly 1.17 blogs per day, or makes 2.62 comments. Are you more or less active? Depending on your answer, you can judge for yourself whether you are doing better or worse than the average.
At the present price of $2.50 per steem the financial rewards for blogging are pretty mediocre. There is only so much money to go around, and only a small number can justify giving up their day jobs to blog.
On the other hand, as more users join steemit, the demand for steem is likely to rise. This means that the $2.50 you earned today might be worth $100 next year. It could be worth hanging onto those steem! It may seem little at the moment, but it could grow in value.
Here's how things would look if steem was worth USD 100: