Manhattan District Attorney Alvin Bragg says his office's efforts to prevent gun violence across the borough are bearing fruit, as the island is seeing sharp declines in homicides and gun violence over the last several years. In an exclusive sit-down interview with amNewYork, Bragg cited statistics that demonstrate a 60% drop in shootings and a 64% decrease in homicides across the borough since 2021. According to Manhattan's chief prosecutor, th…