The value of Steem as at the beginning of the market on Jan 4, 2018 and at the opening of the market on Feb 4 , 2018 which are $8.12 and $4.38 respectively shows that its value has reduced by 85.3% since the Mathematics is shown below:
$8.12 - $4.38 = $3.74
$3.74/$4.38 * 100% = 85.3%