Complex sentence: The economy was affected by a 3-year-recession from 1991 to 1993 when the economy contracted by 2%, which also became apparent in Switzerland's energy consumption and export growth rates.
Split into simpler sentences: The economy was affected by a 3-year-recession from 1991 to 1993 when the economy contracted by 2%. The contraction also became apparent in Switzerland's energy consumption and export growth rates.