Human Rights Watch, which authored the report, also said that the militant Islamist group is increasing its use of bombs, detonating 14 explosions that killed 423 people during that same period.
The blasts, including several apparent suicide bombings, occurred in a brothel, a technical college, marketplaces and, on two occasions, in venues where people were watching soccer matches.
In other attacks, armed Boko Haram militia opened fire in places of worship and elsewhere in the West African nation.
In May, gunmen allegedly descended on the twin towns of Gamboru-Ngala in armored personnel carriers stolen from the Nigerian military and killed 336 people.
In April, the organization kidnapped 276 girls from a school in Chibok.
The multi-nation effort to find the children has failed, despite international outrage and support, including the social media campaign #BringBackOurGirls.
Boko Haram leaders reportedly are willing to return the young women in exchange for members being held in Nigerian prisons, but such a deal appears highly unlikely.
In addition, recovery seems nearly impossible considering the young women and their captors are hiding within hundreds of miles of dense terrain. And officials say a rescue operation would likely result in the deaths of too many of the young women.
A video obtained Monday by the news media and thought to be made by Boko Harman appears to show fighters mocking the social media campaign.
The State Department last year designated Boko Haram as a terrorist organization. The agency has yet to respond to a question Tuesday about the search.
Human Rights Watch says its numbers are based on field investigations and media reports and that the attacks on civilians stretched across more than 70 towns and villages in northeastern Nigeria, including the federal capital, Abuja.
The group reports three attacks in Abuja, which it says suggests Boko Haram is expanding operations southward. But most of the attacks and casualties appeared to have taken place in Borno State, the birthplace of Boko Haram, where 1,446 people died.
“Boko Haram is effectively waging war on the people of northeastern Nigeria at a staggering human cost,” said Corinne Dufka, the group’s West Africa director.
Widespread poverty, government corruption and lawlessness in the region has given rise to such armed militant groups as Boko Haram, which formed in 2009 and has since tried to impose its authority under Shariah Islamic law.
“The nature and frequency of the attacks indicate the actions of an organized movement,” Human Rights Watch says. “This is evidenced by the presence of convoys of trucks, motorbikes and occasionally armored personnel carriers with well-armed gunmen.