According to rankings, Singapore's economy is the most pro-business and open in the world. Information technology, pharmaceuticals, biotechnology, precision engineering, aerospace, and professional services are the main industries propelling Singapore's economy. Many international corporations have set up their regional headquarters and global R&D facilities in Singapore, including Twitter, Dyson, Tencent, LinkedIn, and Facebook. Singapore's connectivity, strong economy, and considerable influence in the region make it a major economic hub in Asia. Singapore has also been rated by Mercer, the world's top human resource management consulting firm, as the Asian city with the best quality of life.