YEREVAN, September 20. /ARKA/. The average market exchange rate of US dollar against the Armenian dram has dropped today by 0.15 points from September 19 to 478.23 drams, the Central Bank said. It also said the average exchange rate of Euro has fallen from 574.43 drams to 574.40 drams and the average exchange rate of Russian ruble has grown from 8.23 drams to 8.26 drams -0-