In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Response rates according to three sets of criteria were greater with the standard dose ( 55 % - 60 % ) than the low dose ( 25 % - 35 % ) and placebo ( 25 % - 30 % ) .
### Output Text:
Response rates according to three sets of criteria were greater with the standard dose ( 55 % - 60 % ) than the low dose ( 25 % - 35 % ) and placebo ( 25 % - 30 % ) . 