what's the number of patients who have had family hx-breast malig diagnosed until 2 years ago?
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select diagnoses_icd.hadm_id from diagnoses_icd where diagnoses_icd.icd9_code = ( select d_icd_diagnoses.icd9_code from d_icd_diagnoses where d_icd_diagnoses.short_title = 'family hx-breast malig' ) and datetime(diagnoses_icd.charttime) <= datetime(current_time,'-2 year') )