You will be given a definition of a task first, then some input of the task.
This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: Liberia scored a 3.3 on a scale from 10 (highly clean) to 0 (highly corrupt) on the 2010 Corruption Perceptions Index. This gave it a ranking 87th of 178 countries worldwide and 11th of 47 in Sub-Saharan Africa. This score represented a significant improvement since 2007, when the country scored 2.1 and ranked 150th of 180 countries. When seeking attention of a selection of service[clarification needed] providers, 89% of Liberians had to pay a bribe, the highest national percentage in the world according to the organization's 2010 Global Corruption Barometer.
Output:
When was the Corruption Perceptions Index implemented?