The skyscraper index is a way of measuring the state of a country's economy. It works by comparing the height of a country's tallest buildings with the strength of its economy. If the tallest buildings in a country are really tall, then it means that the economy of that country is probably doing really well. On the other hand, if the tallest buildings in a country are not very tall, then it means that the economy of that country is probably not doing so well.