This chart shows the number of I-130s under a 'preference' classification received by USCIS each quarter. It shows that as early as the first quarter of 2020, the California Service Center was receiving 100% of such I-130s. But, at the end of 2021, with comparable comparable volumes, received I-130s are distributed evenly across all 5 service centers (California, Nebraska, Potomac, Texas, Vermont).