sentences:  "Cachuela Esperanza" had the first X-ray unit of Bolivia, and millionaires from Rio de Janeiro und São Paulo were flown in by seaplanes.In the 1920s, when natural rubber was substituted by synthetic rubber gradually, the importance of "Cachuela Esperanza" declined, and with the Bolivian Revolution of 1952 the artificial jungle town sank into insignificance once and for all.Today, "Cachuela Esperanza" has a mere 200 inhabitants.