He was also influential in laying the foundations of economic statistics, as exemplified in his popular The Making of Index Numbers. In fact he was not content with just theory: he went on to found by himself the Index Number Institute that engaged in computing commodity price indices, and thus became one of the most popular providers of market information at the time.
Less than 0.2% of the global bond market is currently explicitly designated as “green", which means that the bond is explicitly issued to finance an ecological project. That raises the question whether the public sector should support or even promote the development of the market. As regards the issuance of green bonds, promotional banks like the German KfW are playing a pioneering role.