Ok. I made calculations:
https://docs.google.com/spreadsheet/ccc?key=0At61Hg_Wl-L3dFc0aWo1bkxSbEMyd2x4eVVLM0w2bmc

Graph is following:
![Screen Shot 2013-01-10 at 11 20 00 PM](https://f.cloud.github.com/assets/108065/58288/84c1465a-5b6b-11e2-9293-902f4ed4b073.png)