Last Year's Models

From the Joongang Ilbo:

Discarded cellphones at a KTF mobile phone recycling center in Uiwang, Gyeonggi, await reassembly for export or disassembly to retrieve valuable parts, such as gold. About 14 million cell phones are discarded every year, of which 24 percent are recycled.

If there are about 40 million cell phones in use in Korea, then it would seem around 30% of them are replaced every year.