More Violence Against Nature...

Cantos XIV (Circle 7:3)
Beginning after line 129

My Master and I came next to a place
of blasphemous sins against nature
where cries of the punished echoed below.
Ever cautious we descended further
the first that I did see was an ugly man1
covered in lime2, all his hair singed off.
Clamped on each of his feet rests a bear trap3
his attempts to flee the arrows and bullets
from demons fail, but they kill him not yet
for after laying in agony, letting
his heart leak out every final drop (as
he had to God’s creatures explains Virgil).
Once his heart ceases, demons cut off
his head, mounting it, watching his body
become the hunted by the demons.
And so past the ugly man was a sight far
too disgusting for the eyes, I turned
quickly away, averting my gaze.
Virgil comforted me saying: ‘Do not
turn your face in disgust, you must ask her
first what she has done.’ Following my master,
I turned facing her, all that was exposed
was raw muscle and partial bone; her skin
lay piled next to her. Walking closer
I saw hunched over more like her sewing
their skin together, though seeming to feel
every stitch4. Naturally I questioned
the woman. Adriana5 was her name
and she spoke of her sin of wearing the
skin of others to which this is now her
lasting punishment. I replied of course
without pity to which Virgil and I
carried onward down through the circles of hell.


1 Mainly sports hunters and recreational hunters included in this category (Note that they are not always men).
2Sinner is dumped into a large lime pit, which is used to melt the hair off hides in the process of making leather.
3Bear trap is commonly used in hunting to trap larger animal, it clamps down on the victim with extreme force and does not come released.
4Although their skin has been stripped off of them, they still have connection to their skin through touch, thus when they must sew their skin together, creating the fashions that they wore in other skins, they feel every pain.
5Adriana of Adriana Furs and all other fur-wearing people included.


Question:
How many years did it take for Dante to finish this trilogy?

Between 1308-1321
http://en.wikipedia.org/wiki/The_Divine_Comedy