Gmail Storage to 13 GB by the End of 2007

Regarding the post on the Gmail Official Blog, I made a simple calculation.
Based on my calculation Gmail will reach 13 gigabytes at the end of the 2007.

The formula/steps I used in calculation is
1. I get the increase value of the Gmail storage counter (I get the average out of the values I got)
2. I get the seconds per day
3. I get the total number of days up to the December 31, 2007 from now
4. I multiply the results of the step 1 and step 2, I got the total increased storage per day
5. I multiply the result of the step 4 by the result of step 3; I got the total increased storage up to December 31, 2007
6. I add the result of the step 5 by the current storage capacity

Ex.
1. 0.001508, 0.001507, 0.001509 (unit in megabytes)
So I summed it up and divided by 3, I got 0.001508 megabytes
2. 60 seconds * 60 minutes * 24 hours
So I got 86400 seconds in a day
3. I count the total number of day from October 19, 2007 up to December 31, 2007
I got 73 days
4. I multiply 0.001508 megabytes by 86400 seconds
I got 130.2912 megabytes
5. I multiply 130.2912 megabytes by 73 days
I got 9511.2576 megabytes
6. I add 9511.258 megabytes by 3783.346605 megabytes
I got 13294.604205 megabytes

PS. this is only my estimation