Complex sentence: In 1990, gas turbine power stations comprised 5% of the UK's generating capacity, by 2002 the new CCGT power stations comprised 28% of UK generating capacity with gas turbines comprising a further 2%.
Split into simpler sentences: In 1990, gas turbine power stations made up 5% of the UK's generating capacity. By 2002, the new CCGT power stations made up 28% UK generating capacity; gas turbines accounted for a further 2%.