For example, some 200 polluting factories have been closed, switched to new kinds of cleaner production, or moved out of the city over the past seven years. Moreover, as a result of a $17 billion investment, more than 90% of the city’s wastewater is now treated, more than 50% of the city is forested, and natural gas accounts for more than 60% of energy generation, up from roughly 45% in 2000.