registered in the World Directory of Medical Schools (WDOM) In comparison, regular graduates from medical schools in the United States and Canada need to complete USMLE Steps 1 and 2 as well, but can participate in the NRMP while still doing their final year of medical school before acquiring their medical diplomas. In effect, taking regular administrative delays into account, and with residency programs starting around July, there is a gap of at least half a year for IMGs between graduation from medical school and beginning of a residency program. Those IMGs who have passed the necessary USMLE exams, obtained the ECFMG certification and matched to a residency position can then begin training in a residency program. USMLE exam scores are considered in the matching process for entering a residency program. One study came to the result that almost half of IMGs were unsuccessful in their first attempts in the pursuit of a U.S. residency position, and three-quarters began a residency after five years. It also indicated that IMGs were considerably older when they first applied for a residency position than are most U.S. medical graduates, with mean age of IMGs when the ECFMG certificate was issued being 32.4 years, with a standard deviation of 5.8 years. Applicants to residency programs in California previously needed a (PTAL), colloquially called a "California Letter". PTAL was discontinued by the California Medical Board in 2020. Applicants now need a post-graduate training license similar to the one issued by other states. Concerning visa requirements, non-U.S.-citizen doctors usually enter via the J1 or the H-1B visa. The J1 requires a 2-year home residence after completion of training in the U.S. The H-1B visa does not have this 2-year home residence requirement, but further requires the USMLE Step 3. And initially, a B-1 visitor visa is required for taking the USMLE Step 2 clinical skills examination and the USMLE Step 3. Indian physicians with a MBBS are qualified to take the USMLE. However, since the 2010s, the process of obtaining a license has become increasingly complicated India has exported more physicians to the United States than any other foreign nation. Origin by country The largest number of licensed International Medical Graduates comes from schools in India, the Caribbean, Pakistan and the Philippines. Medical graduates from schools in the Caribbean have had the largest growth in the period between 2010 and 2018. Their numbers have increased from