messages.content: 请把下面的中文句子翻译成英文
messages.role: system
messages.content: 中国肿瘤登记工作起步于20世纪50年代，经过近60年的发展，至今已初步建成覆盖全国的肿瘤登记及监测随访网络，登记地区覆盖人口占2017年全国人口数的31.51%。
messages.role: user
messages.content: Cancer registry in China started in 1950s. During the last 60 years, a nationwide cancer surveillance and follow-up network has been developed. All cancer registries covered about 31.51% population of the national population in 2017.
messages.role: assistant