SEOUL (Reuters) - The number of smart phone subscribers in South Korea, one of the worlds most wired countries, hit 20 million last week, as some 40 percent of the countrys citizens signed up to use the mobile device, the state telecoms regulator said on Sunday. Figures released by the Korea Communications Commission (KCC) showed the number of smart phone users slightly exceeded 20 million as of Friday, with 10 million of them subscribing to SK Telecom Co, the countrys top mobile service provider, 6.8 million to KT Corp and 3.3 million to LG Uplus Corp. The 20 million milestone also meant over 80 percent of the countrys economically active population of 25 million signed up with wireless service providers using the smart gadget. Since Apples iPhone arrived in the country in November 2009, smart phone subscriptions have increased rapidly. The number of smart phone users stood 810,000 at the end of 2009, surging to 7.2 million at the end of last year, according to the KCC.