instruction: How many business rates are related to each cmi cross reference? List cross reference id, master customer id and the n
response: SELECT T2.cmi_cross_ref_id, T2.master_customer_id, COUNT(*) FROM business_rates AS T1 JOIN cmi_cross_references AS T2 ON T1.cmi_cross_ref_id = T2.cmi_cross_ref_id GROUP BY T2.cmi_cross_ref_id