求翻译：1978年，全国发电装机容量仅5700万千瓦，每年发电量2566亿千瓦时；到1999年底，全国发电装机容量达到29877万千瓦，年发电量达到12331亿千瓦时，居世界第二位。是什么意思？

In 1978, the national power generation capacity is only 57 million kilowatts, an annual generating capacity of 256.6 billion kwh; to the end of 1999, national power generation capacity reached 298.77 million kilowatts, annual energy output reached 1.2331 trillion kwh, ranking second in the world.

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In 1978, national electricity generation installed capacity only 57,000,000 kilowatts, every year power rate 256,600,000,000 kilowatt-hours; To the end of year 1999, the national electricity generation installed capacity achieved 298,770,000 kilowatts, the year power rate achieved 1,233,100,000,000

In 1978, the national power generation capacity is only 57 million-kilowatt, when the annual electricity production of 256.6 billion-kilowatt; by the end of 1999, the national power generation capacity reaches 298.77 million-kilowatt, when the annual energy output reached 1.2331 trillion-kilowatt, r

In 1978, the national power generation capacity is only 57 million kilowatts, an annual generating capacity of 256.6 billion kwh; to the end of 1999, national power generation capacity reached 298.77 million kilowatts, annual energy output reached 1.2331 trillion kwh, ranking second in the world.