BROOKLYN - It?s a start. About 200 physicians throughout Brooklyn and city have signed up to use electronic medical records, but by the end of the year, Mayor Michael Bloomberg wants to see that number jump to 2,000. Bloomberg said electronic records will be more efficient by reducing paperwork, cutting down on unnecessary tests and preventing medical mix-ups. To qualify, at least 30 percent of a provider?s patients must be either uninsured or on Medicaid. Doctor Sumir Saghal, who started using electronic records in December, said he is all for them. ?I sent an electronic prescription and then I faxed the list of medication to the nurse and printed out a copy for the patient,? Saghal said.