Please Help (Experience Point Question)

Dear friends, I have a question regarding work experience for Skilled Worker category. I would appreciate your kind help.

During 2001, I earned a full-time (40 hours/week) experience for 15 months (in qualified NOC category) from my home country in Africa. I am wondering how many points can i get from this alone.
Also, i have some other recent part-time experiences from US, I am curious how many points those will be eligible for.

The following recent experiences are from my recent MS and PhD programs in the US, in which i had a part time RA jobs in a broken contracts but in a continuous employment with the same departments for considerable time. Those were

Aug. 2002 - Dec. 2002 for 15 hours/week with employer A
Janu. 2003- May 2003 for 15 hours/week with employer A
June 2003- Aug 2003 for 37.5 hours/week with employer A
Aug 2003 - Dec. 2003 for 15 hours/week with employer A

Jan. 2006 - present (July 2008) for 20 hours/week with employer B

I could not come up with the final score i will get from those experiences. Different people suggested me different, and now i hope this will be solved from this forum.

Roger