Time frame is an essential factor for assessing if it's a success. In 5 years? 10 year? 20 years? 50 years? What if the previous level was actually very high, say 50%, and the job was to increase from the low level 10% to 15%? With different time frames for evaluation, even someone do not have in-depth knowledge of a topic, she/he could still have some facts to raise valuable questions which can lead to an answer closer to the truth, if there is any we can find eventually. Sorry to not answer your question directly, but I think a different angle might be a better start point.