The economies of Asia’s prosperous city-states Hong Kong and Singapore seem set to be about the worst economic performers in Asia this year as world trade falters and the air goes out of once buoyant property markets. Hong Kong’s Financial Secretary, John Tsang, has just forecast growth of 1-2 percent in 2016 after 2.5 percent last year. But for once the official forecast may prove optimistic. The evidence of sharp slowdown is almost everywhere. For a start, the Hong Kong dollar money supply has been static since last May and loans and advances for local use have increased only marginally, with continued growth in residential mortgages offsetting declines in other sectors.