The graph above goes back almost 20 years so it captures the entirety of the current gold bull market which began in 2001. You can see that in the late 1990s, sentiment languished below 40 which meant that there was excessive public pessimism towards gold. It comes as no surprise then that the current bull market in gold was launched in 2001 from terrible public sentiment. From 2001 to 2011, we saw the price of gold rise from $250/oz to $1,900/oz - a gain of over 600%. During this run, gold sentiment mostly fluctuated within the "normal" range between 40 and 75.
After the 2011 market top, however, sentiment plunged to levels not seen in 20 years, dropping all the way to single digits (albeit briefly). Sentiment has remained at these excessively pessimistic levels for 2.5 years now - quite similar to the 1997-2000 period. If bull markets are born out of public pessimism, then you can make the argument that we are on the cusp of a new bullish breakout in gold.