When it comes to graduation rates in New Haven – the Cooperative High School and the Sound School are tops – with graduation rates over 90 percent in 2012, according to data provided by the New Haven Public Schools. Overall the city’s high school graduation rate increased six percentage points to 70.5 percent in 2012, the data shows. And at the same time the dropout rate fell by 4.2 percentage points to 21 percent, according to the data. The graduation rate at Wilbur Cross High School improved the most by 10 percentage points in just one year from 60 percent to 70 percent. For the past 5 years graduation rates at the Sound School have remained steady — hovering around 90 percent each year.