GradNation, a campaign aimed at raising the nation's high school graduation rate to 90 percent by 2020, released a data brief highlighting trends among low-income, disabled and minority students.

Graduation rates reached a record-high 82.3 percent in 2014, up nearly one percent from the 2012-13 school year and 10 percentage points from the start of the millennium. Iowa led the way with a 90.5 percent graduation rate, and 28 other states followed by equaling or exceeding the national average.

While researchers found that half of states are on pace to reach GradNation's goal, the rate at which their goal is met slowed to the point that it needs to increase annually by 1.3 percent.

"High school graduation rates continue to climb thanks to the work of millions of students and adults, but low graduation rates for large groups of students still plague all regions of the nation," Robert Balfanz, study co-author and director of the Everyone Graduates Center, said in a statement. "Our goal is a 90 percent graduation rate for all groups of students."

Latinos are the fastest-growing demographic in the United States, and they have continually exceeded the national rate of improvement since 2011, yet they are not on track to reach 90 percent in four years. In fact, 11 states graduated less than 70 percent of Latinos; the gap between Latino and White students stands at 10.9 percent, down slightly from 11.4 percent in 2013. African-Americans and Caucasians have a bigger gap to bridge with a difference of 15.9 percentage points.

"These numbers tell a cautionary story of tremendous progress and sobering challenge," added John Bridgeland, CEO of Civic Enterprises, also a co-author. "Yes, we are making national progress, but too many students are being left behind in today's economy. Without a high school diploma, they won't have a chance at the American dream."

Whereas growing up in low-income neighborhoods used to deter Latinos from graduating, the number of students dropping out from low-performing schools has declined.

Nationwide, there are about 1,000 "dropout factories," or schools where the 12th grade enrollment rate is 60 percent less than the enrollment rate of when the students were freshmen. Just one year ago there were 1,200 "dropout factories" affecting over a million students; in 2002, more than 2,500 schools saw 2.5 million drop out.

GradNation's most recent study found that number to fall below one million for the first time, though it disproportionately includes Latinos and African-Americans.

"Of the roughly 924,000 students in low-graduation-rate high schools, 65 percent were low-income and 63 percent African-American or Hispanic/Latino," researchers wrote. "It is clear these schools and students need greater support to improve and become places where graduation is the norm."