1. is it normal that you have about 8 job interviews and you only get offer by two ?

2. What is the acceptable ejection ratio?

1. No, it's not normal to get that high a percentage of offers. Most people will have many interviews before they get one offer.

2. [shrug]

Not being helpful, but you could take a humorous approach to your situation and send them a letter rejecting their rejection like this one:

Herbert A. Millington
Chair - Search Committee
412A Clarkson Hall
Whitson University
College Hill, MA 34109

Dear Professor Millington,

Thank you for your letter of March 16. After careful
consideration, I regret to inform you that I am unable to accept
your refusal to offer me an assistant professor position in your
department.

This year I have been particularly fortunate in receiving an
unusually large number of rejection letters. With such a varied
and promising field of candidates it is impossible for me to accept
all refusals.

Despite Whitson's outstanding qualifications and previous
experience in rejecting applicants, I find that your rejection does
not meet my needs at this time. Therefore, I will assume the
position of assistant professor in your department this August.

I look forward to seeing you then.

Best of luck in rejecting future applicants.

Sincerely,

Chris L. Jensen

(Source)

Meatsack, aside from your actual point when posting that, it was hilarious! Good one! :)

In my own experience, I think about 40% of applications I send out (for open positions they're soliciting to fill, not including "we're always hiring! Send us your resume!" situations) turn into phone-screens or in-person interviews, and of those about 40% have made some kind of offer. So that's a little less than 2 out of 10 applications end up in an offer. Of the offers, about a third offered unacceptable terms (low pay, or some indication of unacceptable-to-me work-life balance), or occasionally I've had multiple offers in the same time window, and had to reject the weaker offer.

All in all, I'd say that's about 1 in 15 applications that has become a job.

Of course, you'll see more or less action depending on how well-qualified you actually are for the positions you're applying for, how well your resume presents you and your skills, how the interviewer perceives your personality traits, and how low a wage you might be willing to accept.

All that said, rightly or wrongly, usually the bar to hire a foreigner living in another country is higher than for a native (or someone with a similar cultural background), even if they've been naturalized. Its simply that all things being equal, someone of one background fits more easily into a team that's predominantly of a similar background. As a foreigner, you simply have a harder time convincing them of your worth. Often, engineering practices differ by company and by team, and new necessary skills can be taught, so you do not win a job on your technical merits alone; the so-called "team fit" and aptitude for learning and problem solving are usually all that an interviewer is actually weighting after an interview (In general you don't get an interview unless they think you've got the technical skills, and any technical questions during an interview are there to gut-check that you didn't lie about your skills, and to watch you problem-solve). If you don't get technical questions during an interview, they either believe you have the skills you say you have, or (perhaps more likely) they choose to evaluate team-fit first, and they're passing over you before getting to that part.