More than 3,000 refugees, migrants and asylum seekers died or went missing last year while trying to reach Europe via Mediterranean and Atlantic sea routes, a UN refugee agency report showed Friday, reporting the highest toll in recent years.

The report estimated more than 3,535 refugees trying to reach Europe via the sea or ocean have died or gone missing⁠—the highest number since the agency began releasing its estimated tolls in 2019. The report states that this number could be much higher and that accurate numbers are difficult to determine due to a lack of resources. “The absence of a global and connected system to register and document the loss of persons along these land and sea routes inhibits an understanding of the scale and substance of how loss of life happens and might be prevented.”

The report highlights the need for more sophisticated methods of tracking refugee sea voyages. The agency claims that this could be done through a more cooperative and sophisticated system of monitoring refugee movement and sea patterns to avoid dangerous situations.

Additionally, the agency called for increased cooperation from Italy and Spain, the two European countries with the highest numbers of incoming refugees. If both Italy and Spain were to share their refugee data with the UN agency, the report claims there might be a greater chance of responding to the needs of refugees.