If your search is just beginning, indicate to the interviewer, "I just started my search, this is my first interview. I am being very selective with the companies with which I am interviewing." If you have had a series of interviews and no offers, be careful not to say, "I have interviewed with 15 companies." Then the interviewer may ask if you have had an offer. If you answer, "No", the interviewer might think, "Well, 15 companies did not want him/her, why would I want him/her?"
Develop a strategy that indicates that you have started a search, contacted several companies, had several interviews, and are expecting secondary rounds with several companies. Keep your job search information confidential because it is a confidential matter. Revealing information also might indicate you have loose lips and may talk about confidential matters of the company.